RE: [st-ericsson] v4l2 vs omx for camera
On Mon, 2011-02-28 at 09:50 +0100, Marek Szyprowski wrote: Hello, [...] I'm not sure that highmem is the right solution. First, this will force systems with rather small amount of memory (like 256M) to use highmem just to support DMA allocable memory. It also doesn't solve the issue with specific memory requirement for our DMA hardware (multimedia codec needs video memory buffers from 2 physical banks). Could you explain why a codec would require memory buffers from 2 physical banks ? Thanks, Edward The relocation issue has been already addressed in the last CMA patch series. Michal managed to create a framework that allowed to relocate on demand any pages from the CMA area. Best regards -- Marek Szyprowski Samsung Poland RD Center -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: [st-ericsson] v4l2 vs omx for camera
Hello, On Tuesday, March 01, 2011 11:26 AM Edward Hervey wrote: On Mon, 2011-02-28 at 09:50 +0100, Marek Szyprowski wrote: Hello, [...] I'm not sure that highmem is the right solution. First, this will force systems with rather small amount of memory (like 256M) to use highmem just to support DMA allocable memory. It also doesn't solve the issue with specific memory requirement for our DMA hardware (multimedia codec needs video memory buffers from 2 physical banks). Could you explain why a codec would require memory buffers from 2 physical banks ? Well, this is rather a question to hardware engineer who designed it. I suspect that the buffers has been split into 2 regions and placed in 2 different memory banks to achieve the performance required to decode/encode full hd h264 movie. Video codec has 2 AXI master interfaces and I expect it is able to perform 2 transaction to the memory at once. Best regards -- Marek Szyprowski Samsung Poland RD Center -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: [st-ericsson] v4l2 vs omx for camera
Hello, On Saturday, February 26, 2011 8:20 PM Nicolas Pitre wrote: On Sat, 26 Feb 2011, Kyungmin Park wrote: On Sat, Feb 26, 2011 at 2:22 AM, Linus Walleij linus.wall...@linaro.org wrote: 2011/2/24 Edward Hervey bilb...@gmail.com: What *needs* to be solved is an API for data allocation/passing at the kernel level which v4l2,omx,X,GL,vdpau,vaapi,... can use and that userspace (like GStreamer) can pass around, monitor and know about. I think the patches sent out from ST-Ericsson's Johan Mossberg to linux-mm for HWMEM (hardware memory) deals exactly with buffer passing, pinning of buffers and so on. The CMA (Contigous Memory Allocator) has been slightly modified to fit hand-in-glove with HWMEM, so CMA provides buffers, HWMEM pass them around. Johan, when you re-spin the HWMEM patchset, can you include linaro-dev and linux-media in the CC? I think there is *much* interest in this mechanism, people just don't know from the name what it really does. Maybe it should be called mediamem or something instead... To Marek, Can you also update the CMA status and plan? The important thing is still Russell don't agree the CMA since it's not solve the ARM different memory attribute mapping issue. Of course there's no way to solve the ARM issue. There are at least two ways to solve that issue, and I have suggested both on the lak mailing list already. 1) Make the direct mapped kernel memory usable by CMA mapped through a page-sized two-level page table mapping which would allow for solving the attributes conflict on a per page basis. That's the solution I work on now. I've also suggested this in the last CMA discussion, however there was no response if this is the right way 2) Use highmem more aggressively and allow only highmem pages for CMA. This is quite easy to make sure the target page(s) for CMA would have no kernel mappings and therefore no attribute conflict. Furthermore, highmem pages are always relocatable for making physically contiguous segments available. I'm not sure that highmem is the right solution. First, this will force systems with rather small amount of memory (like 256M) to use highmem just to support DMA allocable memory. It also doesn't solve the issue with specific memory requirement for our DMA hardware (multimedia codec needs video memory buffers from 2 physical banks). The relocation issue has been already addressed in the last CMA patch series. Michal managed to create a framework that allowed to relocate on demand any pages from the CMA area. Best regards -- Marek Szyprowski Samsung Poland RD Center -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
On Saturday 26 February 2011 13:12:42 Hans Verkuil wrote: On Friday, February 25, 2011 18:22:51 Linus Walleij wrote: 2011/2/24 Edward Hervey bilb...@gmail.com: What *needs* to be solved is an API for data allocation/passing at the kernel level which v4l2,omx,X,GL,vdpau,vaapi,... can use and that userspace (like GStreamer) can pass around, monitor and know about. I think the patches sent out from ST-Ericsson's Johan Mossberg to linux-mm for HWMEM (hardware memory) deals exactly with buffer passing, pinning of buffers and so on. The CMA (Contigous Memory Allocator) has been slightly modified to fit hand-in-glove with HWMEM, so CMA provides buffers, HWMEM pass them around. Johan, when you re-spin the HWMEM patchset, can you include linaro-dev and linux-media in the CC? Yes, please. This sounds promising and we at linux-media would very much like to take a look at this. I hope that the CMA + HWMEM combination is exactly what we need. Once again let me restate what I've been telling for some time: CMA must be *optional*. Not all hardware need contiguous memory. I'll have a look at the next HWMEM version. -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
On Sunday, February 27, 2011 20:49:37 Arnd Bergmann wrote: On Saturday 26 February 2011, Edward Hervey wrote: Are there any gstreamer/linaro/etc core developers attending the ELC in San Francisco in April? I think it might be useful to get together before, during or after the conference and see if we can turn this discussion in something more concrete. It seems to me that there is an overall agreement of what should be done, but that we are far from anything concrete. I will be there and this was definitely a topic I intended to talk about. See you there. I'll also be there. Should we organize an official BOF session for this and invite more people? I think that is an excellent idea. Do you want to organize that? (Always the penalty for suggesting this first :-) ) Regards, Hans -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
On Sunday 27 February 2011 20:49:37 Arnd Bergmann wrote: On Saturday 26 February 2011, Edward Hervey wrote: Are there any gstreamer/linaro/etc core developers attending the ELC in San Francisco in April? I think it might be useful to get together before, during or after the conference and see if we can turn this discussion in something more concrete. It seems to me that there is an overall agreement of what should be done, but that we are far from anything concrete. I will be there and this was definitely a topic I intended to talk about. See you there. I'll also be there. Should we organize an official BOF session for this and invite more people? Any chance of an IRC backchannel and a live audio/video stream for those of us who won't be there ? -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
On Monday, February 28, 2011 11:11:47 Laurent Pinchart wrote: On Saturday 26 February 2011 13:12:42 Hans Verkuil wrote: On Friday, February 25, 2011 18:22:51 Linus Walleij wrote: 2011/2/24 Edward Hervey bilb...@gmail.com: What *needs* to be solved is an API for data allocation/passing at the kernel level which v4l2,omx,X,GL,vdpau,vaapi,... can use and that userspace (like GStreamer) can pass around, monitor and know about. I think the patches sent out from ST-Ericsson's Johan Mossberg to linux-mm for HWMEM (hardware memory) deals exactly with buffer passing, pinning of buffers and so on. The CMA (Contigous Memory Allocator) has been slightly modified to fit hand-in-glove with HWMEM, so CMA provides buffers, HWMEM pass them around. Johan, when you re-spin the HWMEM patchset, can you include linaro-dev and linux-media in the CC? Yes, please. This sounds promising and we at linux-media would very much like to take a look at this. I hope that the CMA + HWMEM combination is exactly what we need. Once again let me restate what I've been telling for some time: CMA must be *optional*. Not all hardware need contiguous memory. I'll have a look at the next HWMEM version. Yes, it is optional when you look at specific hardware. On a kernel level however it is functionality that is required in order to support all the hardware. There is little point in solving one issue and not the other. Regards, Hans -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
On Monday 28 February 2011 11:21:52 Hans Verkuil wrote: On Monday, February 28, 2011 11:11:47 Laurent Pinchart wrote: On Saturday 26 February 2011 13:12:42 Hans Verkuil wrote: On Friday, February 25, 2011 18:22:51 Linus Walleij wrote: 2011/2/24 Edward Hervey bilb...@gmail.com: What *needs* to be solved is an API for data allocation/passing at the kernel level which v4l2,omx,X,GL,vdpau,vaapi,... can use and that userspace (like GStreamer) can pass around, monitor and know about. I think the patches sent out from ST-Ericsson's Johan Mossberg to linux-mm for HWMEM (hardware memory) deals exactly with buffer passing, pinning of buffers and so on. The CMA (Contigous Memory Allocator) has been slightly modified to fit hand-in-glove with HWMEM, so CMA provides buffers, HWMEM pass them around. Johan, when you re-spin the HWMEM patchset, can you include linaro-dev and linux-media in the CC? Yes, please. This sounds promising and we at linux-media would very much like to take a look at this. I hope that the CMA + HWMEM combination is exactly what we need. Once again let me restate what I've been telling for some time: CMA must be *optional*. Not all hardware need contiguous memory. I'll have a look at the next HWMEM version. Yes, it is optional when you look at specific hardware. On a kernel level however it is functionality that is required in order to support all the hardware. There is little point in solving one issue and not the other. I agree. What I meant is that we need to make sure there's no HWMEM - CMA dependency. -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
On Saturday 26 February 2011, Edward Hervey wrote: Are there any gstreamer/linaro/etc core developers attending the ELC in San Francisco in April? I think it might be useful to get together before, during or after the conference and see if we can turn this discussion in something more concrete. It seems to me that there is an overall agreement of what should be done, but that we are far from anything concrete. I will be there and this was definitely a topic I intended to talk about. See you there. I'll also be there. Should we organize an official BOF session for this and invite more people? Arnd -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
On Friday, February 25, 2011 18:22:51 Linus Walleij wrote: 2011/2/24 Edward Hervey bilb...@gmail.com: What *needs* to be solved is an API for data allocation/passing at the kernel level which v4l2,omx,X,GL,vdpau,vaapi,... can use and that userspace (like GStreamer) can pass around, monitor and know about. I think the patches sent out from ST-Ericsson's Johan Mossberg to linux-mm for HWMEM (hardware memory) deals exactly with buffer passing, pinning of buffers and so on. The CMA (Contigous Memory Allocator) has been slightly modified to fit hand-in-glove with HWMEM, so CMA provides buffers, HWMEM pass them around. Johan, when you re-spin the HWMEM patchset, can you include linaro-dev and linux-media in the CC? Yes, please. This sounds promising and we at linux-media would very much like to take a look at this. I hope that the CMA + HWMEM combination is exactly what we need. Regards, Hans I think there is *much* interest in this mechanism, people just don't know from the name what it really does. Maybe it should be called mediamem or something instead... Yours, Linus Walleij -- Hans Verkuil - video4linux developer - sponsored by Cisco -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
Hi, On Fri, Feb 18, 2011 at 6:39 PM, Robert Fekete robert.fek...@linaro.org wrote: To make a long story short: Different vendors provide custom OpenMax solutions for say Camera/ISP. In the Linux eco-system there is V4L2 doing much of this work already and is evolving with mediacontroller as well. Then there is the integration in Gstreamer...Which solution is the best way forward. Current discussions so far puts V4L2 greatly in favor of OMX. Please have in mind that OpenMAX as a concept is more like GStreamer in many senses. The question is whether Camera drivers should have OMX or V4L2 as the driver front end? This may perhaps apply to video codecs as well. Then there is how to in best of ways make use of this in GStreamer in order to achieve no copy highly efficient multimedia pipelines. Is gst-omx the way forward? Let the discussion continue... We are talking about 3 different layers here which don't necessarily overlap. You could have a v4l2 driver, which is wrapped in an OpenMAX IL library, which is wrapped again by gst-openmax. Each layer is different. The problem here is the OMX layer, which is often ill-conceived. First of all, you have to remember that whatever OMX is supposed to provide, that doesn't apply to camera; you can argue that there's some value in audio/video encoding/decoding, as the interfaces are very simple and easy to standardize, but that's not the case with camera. I haven't worked with OMX camera interfaces, but AFAIK it's very incomplete and vendors have to implement their own interfaces, which defeats the purpose of OMX. So OMX provides nothing in the camera case. Secondly, there's no OMX kernel interface. You still need something between kernel to user-space, the only established interface is v4l2. So, even if you choose OMX in user-space, the sensible choice in kernel-space is v4l2, otherwise you would end up with some custom interface which is never good. And third, as Laurent already pointed out; OpenMAX is _not_ open. The community has no say in what happens, everything is decided by a consortium, you need to pay money to be in it, to access their bugzilla, to subscribe to their mailing lists, and to get access to their conformance test. If you forget all the marketing mumbo jumbo about OMX, at the of the day what is provided is a bunch of headers (and a document explaining how to use them). We (the linux community) can come up with a bunch of headers too, in fact, we already do much more than that with v4l2, the only part missing is encoders/decoders, which if needed could be added very easily (Samsung already does AFAIK). Right? Cheers. -- Felipe Contreras -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
Hi, On Thu, Feb 24, 2011 at 3:04 PM, Hans Verkuil hverk...@xs4all.nl wrote: On Thursday, February 24, 2011 13:29:56 Linus Walleij wrote: 2011/2/23 Sachin Gupta sachin.gu...@linaro.org: The imaging coprocessor in today's platforms have a general purpose DSP attached to it I have seen some work being done to use this DSP for graphics/audio processing in case the camera use case is not being tried or also if the camera usecases does not consume the full bandwidth of this dsp.I am not sure how v4l2 would fit in such an architecture, Earlier in this thread I discussed TI:s DSPbridge. In drivers/staging/tidspbridge http://omappedia.org/wiki/DSPBridge_Project you find the TI hackers happy at work with providing a DSP accelerator subsystem. Isn't it possible for a V4L2 component to use this interface (or something more evolved, generic) as backend for assorted DSP offloading? Yes it is, and it has been part of my to-do list for some time now. So using one kernel framework does not exclude using another one at the same time. Whereas something like DSPbridge will load firmware into DSP accelerators and provide control/datapath for that, this can in turn be used by some camera or codec which in turn presents a V4L2 or ALSA interface. Yes, something along those lines can be done. While normally V4L2 talks to hardware it is perfectly fine to talk to a DSP instead. The hardest part will be to identify the missing V4L2 API pieces and design and add them. I don't think the actual driver code will be particularly hard. It should be nothing more than a thin front-end for the DSP. Of course, that's just theory at the moment :-) The pieces are known already. I started a project called gst-dsp, which I plan to split into the gst part, and the part that communicates with the DSP, this part can move to kernel side with a v4l2 interface. It's easier to identify the code in the patches for FFmpeg: http://article.gmane.org/gmane.comp.video.ffmpeg.devel/116798 The problem is that someone has to do the actual work for the initial driver. And I expect that it will be a substantial amount of work. Future drivers should be *much* easier, though. A good argument for doing this work is that this API can hide which parts of the video subsystem are hardware and which are software. The application really doesn't care how it is organized. What is done in hardware on one SoC might be done on a DSP instead on another SoC. But the end result is pretty much the same. Exactly. -- Felipe Contreras -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
On Thu, Feb 24, 2011 at 3:27 PM, Laurent Pinchart laurent.pinch...@ideasonboard.com wrote: Perhaps GStreamer experts would like to comment on the future plans ahead for zero copying/IPC and low power HW use cases? Could Gstreamer adapt some ideas from OMX IL making OMX IL obsolete? perhaps OMX should adapt some of the ideas from GStreamer ;-) I'd very much like to see GStreamer (or something else, maybe lower level, but community-maintainted) replace OMX. Yes, it would be great to have something that wraps all the hardware acceleration and could have support for software codecs too, all in a standard interface. It would also be great if this interface would be used in the upper layers like GStreamer, VLC, etc. Kind of what OMX was supposed to be, but open [1]. Oh wait, I'm describing FFmpeg :) (supports vl42, VA-API, VDPAU, DirectX, and soon OMAP3 DSP) Cheers. [1] http://freedesktop.org/wiki/GstOpenMAX?action=AttachFiledo=gettarget=gst-openmax.png -- Felipe Contreras -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
On Saturday, February 26, 2011 14:38:50 Felipe Contreras wrote: On Thu, Feb 24, 2011 at 3:27 PM, Laurent Pinchart laurent.pinch...@ideasonboard.com wrote: Perhaps GStreamer experts would like to comment on the future plans ahead for zero copying/IPC and low power HW use cases? Could Gstreamer adapt some ideas from OMX IL making OMX IL obsolete? perhaps OMX should adapt some of the ideas from GStreamer ;-) I'd very much like to see GStreamer (or something else, maybe lower level, but community-maintainted) replace OMX. Yes, it would be great to have something that wraps all the hardware acceleration and could have support for software codecs too, all in a standard interface. It would also be great if this interface would be used in the upper layers like GStreamer, VLC, etc. Kind of what OMX was supposed to be, but open [1]. Oh wait, I'm describing FFmpeg :) (supports vl42, VA-API, VDPAU, DirectX, and soon OMAP3 DSP) Cheers. [1] http://freedesktop.org/wiki/GstOpenMAX?action=AttachFiledo=gettarget=gst-openmax.png Are there any gstreamer/linaro/etc core developers attending the ELC in San Francisco in April? I think it might be useful to get together before, during or after the conference and see if we can turn this discussion in something more concrete. It seems to me that there is an overall agreement of what should be done, but that we are far from anything concrete. Regards, Hans -- Hans Verkuil - video4linux developer - sponsored by Cisco -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
On Sat, Feb 26, 2011 at 2:22 AM, Linus Walleij linus.wall...@linaro.org wrote: 2011/2/24 Edward Hervey bilb...@gmail.com: What *needs* to be solved is an API for data allocation/passing at the kernel level which v4l2,omx,X,GL,vdpau,vaapi,... can use and that userspace (like GStreamer) can pass around, monitor and know about. I think the patches sent out from ST-Ericsson's Johan Mossberg to linux-mm for HWMEM (hardware memory) deals exactly with buffer passing, pinning of buffers and so on. The CMA (Contigous Memory Allocator) has been slightly modified to fit hand-in-glove with HWMEM, so CMA provides buffers, HWMEM pass them around. Johan, when you re-spin the HWMEM patchset, can you include linaro-dev and linux-media in the CC? I think there is *much* interest in this mechanism, people just don't know from the name what it really does. Maybe it should be called mediamem or something instead... To Marek, Can you also update the CMA status and plan? The important thing is still Russell don't agree the CMA since it's not solve the ARM different memory attribute mapping issue. Of course there's no way to solve the ARM issue. We really need the memory solution for multimedia. Thank you, Kyungmin Park Yours, Linus Walleij -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
On Sat, 2011-02-26 at 14:47 +0100, Hans Verkuil wrote: On Saturday, February 26, 2011 14:38:50 Felipe Contreras wrote: On Thu, Feb 24, 2011 at 3:27 PM, Laurent Pinchart laurent.pinch...@ideasonboard.com wrote: Perhaps GStreamer experts would like to comment on the future plans ahead for zero copying/IPC and low power HW use cases? Could Gstreamer adapt some ideas from OMX IL making OMX IL obsolete? perhaps OMX should adapt some of the ideas from GStreamer ;-) I'd very much like to see GStreamer (or something else, maybe lower level, but community-maintainted) replace OMX. Yes, it would be great to have something that wraps all the hardware acceleration and could have support for software codecs too, all in a standard interface. It would also be great if this interface would be used in the upper layers like GStreamer, VLC, etc. Kind of what OMX was supposed to be, but open [1]. Oh wait, I'm describing FFmpeg :) (supports vl42, VA-API, VDPAU, DirectX, and soon OMAP3 DSP) Cheers. [1] http://freedesktop.org/wiki/GstOpenMAX?action=AttachFiledo=gettarget=gst-openmax.png Are there any gstreamer/linaro/etc core developers attending the ELC in San Francisco in April? I think it might be useful to get together before, during or after the conference and see if we can turn this discussion in something more concrete. It seems to me that there is an overall agreement of what should be done, but that we are far from anything concrete. I will be there and this was definitely a topic I intended to talk about. See you there. Edward Regards, Hans -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
On Sat, 26 Feb 2011, Kyungmin Park wrote: On Sat, Feb 26, 2011 at 2:22 AM, Linus Walleij linus.wall...@linaro.org wrote: 2011/2/24 Edward Hervey bilb...@gmail.com: What *needs* to be solved is an API for data allocation/passing at the kernel level which v4l2,omx,X,GL,vdpau,vaapi,... can use and that userspace (like GStreamer) can pass around, monitor and know about. I think the patches sent out from ST-Ericsson's Johan Mossberg to linux-mm for HWMEM (hardware memory) deals exactly with buffer passing, pinning of buffers and so on. The CMA (Contigous Memory Allocator) has been slightly modified to fit hand-in-glove with HWMEM, so CMA provides buffers, HWMEM pass them around. Johan, when you re-spin the HWMEM patchset, can you include linaro-dev and linux-media in the CC? I think there is *much* interest in this mechanism, people just don't know from the name what it really does. Maybe it should be called mediamem or something instead... To Marek, Can you also update the CMA status and plan? The important thing is still Russell don't agree the CMA since it's not solve the ARM different memory attribute mapping issue. Of course there's no way to solve the ARM issue. There are at least two ways to solve that issue, and I have suggested both on the lak mailing list already. 1) Make the direct mapped kernel memory usable by CMA mapped through a page-sized two-level page table mapping which would allow for solving the attributes conflict on a per page basis. 2) Use highmem more aggressively and allow only highmem pages for CMA. This is quite easy to make sure the target page(s) for CMA would have no kernel mappings and therefore no attribute conflict. Furthermore, highmem pages are always relocatable for making physically contiguous segments available. Nicolas
Re: [st-ericsson] v4l2 vs omx for camera
2011/2/24 Edward Hervey bilb...@gmail.com: What *needs* to be solved is an API for data allocation/passing at the kernel level which v4l2,omx,X,GL,vdpau,vaapi,... can use and that userspace (like GStreamer) can pass around, monitor and know about. I think the patches sent out from ST-Ericsson's Johan Mossberg to linux-mm for HWMEM (hardware memory) deals exactly with buffer passing, pinning of buffers and so on. The CMA (Contigous Memory Allocator) has been slightly modified to fit hand-in-glove with HWMEM, so CMA provides buffers, HWMEM pass them around. Johan, when you re-spin the HWMEM patchset, can you include linaro-dev and linux-media in the CC? I think there is *much* interest in this mechanism, people just don't know from the name what it really does. Maybe it should be called mediamem or something instead... Yours, Linus Walleij -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
2011/2/23 Sachin Gupta sachin.gu...@linaro.org: The imaging coprocessor in today's platforms have a general purpose DSP attached to it I have seen some work being done to use this DSP for graphics/audio processing in case the camera use case is not being tried or also if the camera usecases does not consume the full bandwidth of this dsp.I am not sure how v4l2 would fit in such an architecture, Earlier in this thread I discussed TI:s DSPbridge. In drivers/staging/tidspbridge http://omappedia.org/wiki/DSPBridge_Project you find the TI hackers happy at work with providing a DSP accelerator subsystem. Isn't it possible for a V4L2 component to use this interface (or something more evolved, generic) as backend for assorted DSP offloading? So using one kernel framework does not exclude using another one at the same time. Whereas something like DSPbridge will load firmware into DSP accelerators and provide control/datapath for that, this can in turn be used by some camera or codec which in turn presents a V4L2 or ALSA interface. Yours, Linus Walleij -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
On Tuesday, February 22, 2011 03:44:19 Clark, Rob wrote: On Fri, Feb 18, 2011 at 10:39 AM, Robert Fekete robert.fek...@linaro.org wrote: Hi, In order to expand this knowledge outside of Linaro I took the Liberty of inviting both linux-media@vger.kernel.org and gstreamer-de...@lists.freedesktop.org. For any newcomer I really recommend to do some catch-up reading on http://lists.linaro.org/pipermail/linaro-dev/2011-February/thread.html (v4l2 vs omx for camera thread) before making any comments. And sign up for Linaro-dev while you are at it :-) To make a long story short: Different vendors provide custom OpenMax solutions for say Camera/ISP. In the Linux eco-system there is V4L2 doing much of this work already and is evolving with mediacontroller as well. Then there is the integration in Gstreamer...Which solution is the best way forward. Current discussions so far puts V4L2 greatly in favor of OMX. Please have in mind that OpenMAX as a concept is more like GStreamer in many senses. The question is whether Camera drivers should have OMX or V4L2 as the driver front end? This may perhaps apply to video codecs as well. Then there is how to in best of ways make use of this in GStreamer in order to achieve no copy highly efficient multimedia pipelines. Is gst-omx the way forward? just fwiw, there were some patches to make v4l2src work with userptr buffers in case the camera has an mmu and can handle any random non-physically-contiguous buffer.. so there is in theory no reason why a gst capture pipeline could not be zero copy and capture directly into buffers allocated from the display V4L2 also allows userspace to pass pointers to contiguous physical memory. On TI systems this memory is usually obtained via the out-of-tree cmem module. Certainly a more general way to allocate buffers that any of the hw blocks (display, imaging, video encoders/decoders, 3d/2d hw, etc) could use, and possibly share across-process for some zero copy DRI style rendering, would be nice. Perhaps V4L2_MEMORY_GEM? There are two parts to this: first of all you need a way to allocate large buffers. The CMA patch series is available (but not yet merged) that does this. I'm not sure of the latest status of this series. The other part is that everyone can use and share these buffers. There isn't anything for this yet. We have discussed this in the past and we need something generic for this that all subsystems can use. It's not a good idea to tie this to any specific framework like GEM. Instead any subsystem should be able to use the same subsystem-independent buffer pool API. The actual code is probably not too bad, but trying to coordinate this over all subsystems is not an easy task. Let the discussion continue... On 17 February 2011 14:48, Laurent Pinchart laurent.pinch...@ideasonboard.com wrote: On Thursday 10 February 2011 08:47:15 Hans Verkuil wrote: On Thursday, February 10, 2011 08:17:31 Linus Walleij wrote: On Wed, Feb 9, 2011 at 8:44 PM, Harald Gustafsson wrote: OMX main purpose is to handle multimedia hardware and offer an interface to that HW that looks identical indenpendent of the vendor delivering that hardware, much like the v4l2 or USB subsystems tries to do. And yes optimally it should be implemented in drivers/omx in Linux and a user space library on top of that. Thanks for clarifying this part, it was unclear to me. The reason being that it seems OMX does not imply userspace/kernelspace separation, and I was thinking more of it as a userspace lib. Now my understanding is that if e.g. OpenMAX defines a certain data structure, say for a PCM frame or whatever, then that exact struct is supposed to be used by the kernelspace/userspace interface, and defined in the include file exported by the kernel. It might be that some alignment also needs to be made between 4vl2 and other OS's implementation, to ease developing drivers for many OSs (sorry I don't know these details, but you ST-E guys should know). The basic conflict I would say is that Linux has its own API+ABI, which is defined by V4L and ALSA through a community process without much thought about any existing standard APIs. (In some cases also predating them.) By the way IL is about to finalize version 1.2 of OpenMAX IL which is more than a years work of aligning all vendors and fixing unclear and buggy parts. I suspect that the basic problem with Khronos OpenMAX right now is how to handle communities - for example the X consortium had something like the same problem a while back, only member companies could partake in the standard process, and they need of course to pay an upfront fee for that, and the majority of these companies didn't exactly send Linux community members to the meetings.
Re: [st-ericsson] v4l2 vs omx for camera
On Tuesday 22 February 2011 03:44:19 Clark, Rob wrote: On Fri, Feb 18, 2011 at 10:39 AM, Robert Fekete wrote: In order to expand this knowledge outside of Linaro I took the Liberty of inviting both linux-media@vger.kernel.org and gstreamer-de...@lists.freedesktop.org. For any newcomer I really recommend to do some catch-up reading on http://lists.linaro.org/pipermail/linaro-dev/2011-February/thread.html (v4l2 vs omx for camera thread) before making any comments. And sign up for Linaro-dev while you are at it :-) To make a long story short: Different vendors provide custom OpenMax solutions for say Camera/ISP. In the Linux eco-system there is V4L2 doing much of this work already and is evolving with mediacontroller as well. Then there is the integration in Gstreamer...Which solution is the best way forward. Current discussions so far puts V4L2 greatly in favor of OMX. Please have in mind that OpenMAX as a concept is more like GStreamer in many senses. The question is whether Camera drivers should have OMX or V4L2 as the driver front end? This may perhaps apply to video codecs as well. Then there is how to in best of ways make use of this in GStreamer in order to achieve no copy highly efficient multimedia pipelines. Is gst-omx the way forward? just fwiw, there were some patches to make v4l2src work with userptr buffers in case the camera has an mmu and can handle any random non-physically-contiguous buffer.. so there is in theory no reason why a gst capture pipeline could not be zero copy and capture directly into buffers allocated from the display Certainly a more general way to allocate buffers that any of the hw blocks (display, imaging, video encoders/decoders, 3d/2d hw, etc) could use, and possibly share across-process for some zero copy DRI style rendering, would be nice. Perhaps V4L2_MEMORY_GEM? This is something we first discussed in the end of 2009. We need to get people from different subsystems around the same table, with memory management specialists (especially for ARM), and lay the ground for a common memory management system. Discussions on the V4L2 side called this the global buffers pool (see http://lwn.net/Articles/353044/ for instance, more information can be found in the linux-media list archives). [snip] Let the discussion continue... On 17 February 2011 14:48, Laurent Pinchart wrote: On Thursday 10 February 2011 08:47:15 Hans Verkuil wrote: On Thursday, February 10, 2011 08:17:31 Linus Walleij wrote: On Wed, Feb 9, 2011 at 8:44 PM, Harald Gustafsson wrote: OMX main purpose is to handle multimedia hardware and offer an interface to that HW that looks identical indenpendent of the vendor delivering that hardware, much like the v4l2 or USB subsystems tries to do. And yes optimally it should be implemented in drivers/omx in Linux and a user space library on top of that. Thanks for clarifying this part, it was unclear to me. The reason being that it seems OMX does not imply userspace/kernelspace separation, and I was thinking more of it as a userspace lib. Now my understanding is that if e.g. OpenMAX defines a certain data structure, say for a PCM frame or whatever, then that exact struct is supposed to be used by the kernelspace/userspace interface, and defined in the include file exported by the kernel. It might be that some alignment also needs to be made between 4vl2 and other OS's implementation, to ease developing drivers for many OSs (sorry I don't know these details, but you ST-E guys should know). The basic conflict I would say is that Linux has its own API+ABI, which is defined by V4L and ALSA through a community process without much thought about any existing standard APIs. (In some cases also predating them.) By the way IL is about to finalize version 1.2 of OpenMAX IL which is more than a years work of aligning all vendors and fixing unclear and buggy parts. I suspect that the basic problem with Khronos OpenMAX right now is how to handle communities - for example the X consortium had something like the same problem a while back, only member companies could partake in the standard process, and they need of course to pay an upfront fee for that, and the majority of these companies didn't exactly send Linux community members to the meetings. And now all the companies who took part in OpenMAX somehow end up having to do a lot of upfront community work if they want to drive the API:s in a certain direction, discuss it again with the V4L and ALSA maintainers and so on. Which takes a lot of time and patience with uncertain outcome, since this process is autonomous from Khronos. Nobody seems to be doing this, I javen't seen a single patch aimed at trying to unify the APIs so far. I don't know
Re: [st-ericsson] v4l2 vs omx for camera
On Thursday 24 February 2011 14:17:12 Hans Verkuil wrote: On Tuesday, February 22, 2011 03:44:19 Clark, Rob wrote: On Fri, Feb 18, 2011 at 10:39 AM, Robert Fekete wrote: Hi, In order to expand this knowledge outside of Linaro I took the Liberty of inviting both linux-media@vger.kernel.org and gstreamer-de...@lists.freedesktop.org. For any newcomer I really recommend to do some catch-up reading on http://lists.linaro.org/pipermail/linaro-dev/2011-February/thread.html (v4l2 vs omx for camera thread) before making any comments. And sign up for Linaro-dev while you are at it :-) To make a long story short: Different vendors provide custom OpenMax solutions for say Camera/ISP. In the Linux eco-system there is V4L2 doing much of this work already and is evolving with mediacontroller as well. Then there is the integration in Gstreamer...Which solution is the best way forward. Current discussions so far puts V4L2 greatly in favor of OMX. Please have in mind that OpenMAX as a concept is more like GStreamer in many senses. The question is whether Camera drivers should have OMX or V4L2 as the driver front end? This may perhaps apply to video codecs as well. Then there is how to in best of ways make use of this in GStreamer in order to achieve no copy highly efficient multimedia pipelines. Is gst-omx the way forward? just fwiw, there were some patches to make v4l2src work with userptr buffers in case the camera has an mmu and can handle any random non-physically-contiguous buffer.. so there is in theory no reason why a gst capture pipeline could not be zero copy and capture directly into buffers allocated from the display V4L2 also allows userspace to pass pointers to contiguous physical memory. On TI systems this memory is usually obtained via the out-of-tree cmem module. On the OMAP3 the ISP doesn't require physically contiguous memory. User pointers can be used quite freely, except that they introduce cache management issues on ARM when speculative prefetching comes into play (those issues are currently ignored completely). Certainly a more general way to allocate buffers that any of the hw blocks (display, imaging, video encoders/decoders, 3d/2d hw, etc) could use, and possibly share across-process for some zero copy DRI style rendering, would be nice. Perhaps V4L2_MEMORY_GEM? There are two parts to this: first of all you need a way to allocate large buffers. The CMA patch series is available (but not yet merged) that does this. I'm not sure of the latest status of this series. Some platforms don't require contiguous memory. What we need is a way to allocate memory in the kernel with various options, and use that memory in various drivers (V4L2, GPU, ...) The other part is that everyone can use and share these buffers. There isn't anything for this yet. We have discussed this in the past and we need something generic for this that all subsystems can use. It's not a good idea to tie this to any specific framework like GEM. Instead any subsystem should be able to use the same subsystem-independent buffer pool API. The actual code is probably not too bad, but trying to coordinate this over all subsystems is not an easy task. [snip] Not even different vendor's omx camera implementations are compatible.. there seems to be too much various in ISP architecture and features for this. Another point, and possibly the reason that TI went the OMX camera route, was that a userspace API made it possible to move the camera driver all to a co-processor (with advantages of reduced interrupt latency for SIMCOP processing, and a larger part of the code being OS independent).. doing this in a kernel mode driver would have required even more of syslink in the kernel. But maybe it would be nice to have a way to have sensor driver on the linux side, pipelined with hw and imaging drivers on a co-processor for various algorithms and filters with configuration all exposed to userspace thru MCF.. I'm not immediately sure how this would work, but it sounds nice at least ;-) MCF? What does that stand for? Media Controller Framework I guess. The question is if the Linux kernel and V4L2 is ready to incorporate several HW(DSP, CPU, ISP, xxHW) in an imaging pipeline for instance. The reason Embedded Vendors provide custom solutions is to implement low power non(or minimal) CPU intervention pipelines where dedicated HW does the work most of the time(like full screen Video Playback). A common way of managing memory would of course also be necessary as well, like hwmem(search for hwmem in Linux-mm) handles to pass buffers in between different drivers and processes all the way from sources(camera, video parser/decode) to sinks(display, hdmi, video encoders(record)) (ahh, ok, you have some of the same thoughts as I do regarding sharing buffers
Re: [st-ericsson] v4l2 vs omx for camera
On Thu, Feb 24, 2011 at 10:17 PM, Hans Verkuil hverk...@xs4all.nl wrote: On Tuesday, February 22, 2011 03:44:19 Clark, Rob wrote: On Fri, Feb 18, 2011 at 10:39 AM, Robert Fekete robert.fek...@linaro.org wrote: Hi, In order to expand this knowledge outside of Linaro I took the Liberty of inviting both linux-media@vger.kernel.org and gstreamer-de...@lists.freedesktop.org. For any newcomer I really recommend to do some catch-up reading on http://lists.linaro.org/pipermail/linaro-dev/2011-February/thread.html (v4l2 vs omx for camera thread) before making any comments. And sign up for Linaro-dev while you are at it :-) To make a long story short: Different vendors provide custom OpenMax solutions for say Camera/ISP. In the Linux eco-system there is V4L2 doing much of this work already and is evolving with mediacontroller as well. Then there is the integration in Gstreamer...Which solution is the best way forward. Current discussions so far puts V4L2 greatly in favor of OMX. Please have in mind that OpenMAX as a concept is more like GStreamer in many senses. The question is whether Camera drivers should have OMX or V4L2 as the driver front end? This may perhaps apply to video codecs as well. Then there is how to in best of ways make use of this in GStreamer in order to achieve no copy highly efficient multimedia pipelines. Is gst-omx the way forward? just fwiw, there were some patches to make v4l2src work with userptr buffers in case the camera has an mmu and can handle any random non-physically-contiguous buffer.. so there is in theory no reason why a gst capture pipeline could not be zero copy and capture directly into buffers allocated from the display V4L2 also allows userspace to pass pointers to contiguous physical memory. On TI systems this memory is usually obtained via the out-of-tree cmem module. Certainly a more general way to allocate buffers that any of the hw blocks (display, imaging, video encoders/decoders, 3d/2d hw, etc) could use, and possibly share across-process for some zero copy DRI style rendering, would be nice. Perhaps V4L2_MEMORY_GEM? There are two parts to this: first of all you need a way to allocate large buffers. The CMA patch series is available (but not yet merged) that does this. I'm not sure of the latest status of this series. Still ARM maintainer doesn't agree these patches since it's not solve the ARM memory different attribute mapping problem. but try to send the CMA v9 patch soon. We need really require the physical memory management module. Each chip vendors use the their own implementations. Our approach called it as CMA, others called it as cmem, carveout, hwmon and so on. I think Laurent's approaches is similar one. We will try it again to merge CMA. Thank you, Kyungmin Park The other part is that everyone can use and share these buffers. There isn't anything for this yet. We have discussed this in the past and we need something generic for this that all subsystems can use. It's not a good idea to tie this to any specific framework like GEM. Instead any subsystem should be able to use the same subsystem-independent buffer pool API. The actual code is probably not too bad, but trying to coordinate this over all subsystems is not an easy task. Let the discussion continue... On 17 February 2011 14:48, Laurent Pinchart laurent.pinch...@ideasonboard.com wrote: On Thursday 10 February 2011 08:47:15 Hans Verkuil wrote: On Thursday, February 10, 2011 08:17:31 Linus Walleij wrote: On Wed, Feb 9, 2011 at 8:44 PM, Harald Gustafsson wrote: OMX main purpose is to handle multimedia hardware and offer an interface to that HW that looks identical indenpendent of the vendor delivering that hardware, much like the v4l2 or USB subsystems tries to do. And yes optimally it should be implemented in drivers/omx in Linux and a user space library on top of that. Thanks for clarifying this part, it was unclear to me. The reason being that it seems OMX does not imply userspace/kernelspace separation, and I was thinking more of it as a userspace lib. Now my understanding is that if e.g. OpenMAX defines a certain data structure, say for a PCM frame or whatever, then that exact struct is supposed to be used by the kernelspace/userspace interface, and defined in the include file exported by the kernel. It might be that some alignment also needs to be made between 4vl2 and other OS's implementation, to ease developing drivers for many OSs (sorry I don't know these details, but you ST-E guys should know). The basic conflict I would say is that Linux has its own API+ABI, which is defined by V4L and ALSA through a community process without much thought about any existing standard APIs. (In some cases also predating them.) By the way IL is about to
Re: [st-ericsson] v4l2 vs omx for camera
Hi,
On Fri, 2011-02-18 at 17:39 +0100, Robert Fekete wrote:
Hi,
In order to expand this knowledge outside of Linaro I took the Liberty
of inviting both linux-media@vger.kernel.org and
gstreamer-de...@lists.freedesktop.org. For any newcomer I really
recommend to do some catch-up reading on
http://lists.linaro.org/pipermail/linaro-dev/2011-February/thread.html
(v4l2 vs omx for camera thread) before making any comments. And sign
up for Linaro-dev while you are at it :-)
To make a long story short:
Different vendors provide custom OpenMax solutions for say Camera/ISP.
In the Linux eco-system there is V4L2 doing much of this work already
and is evolving with mediacontroller as well. Then there is the
integration in Gstreamer...Which solution is the best way forward.
Current discussions so far puts V4L2 greatly in favor of OMX.
Please have in mind that OpenMAX as a concept is more like GStreamer
in many senses. The question is whether Camera drivers should have OMX
or V4L2 as the driver front end? This may perhaps apply to video
codecs as well. Then there is how to in best of ways make use of this
in GStreamer in order to achieve no copy highly efficient multimedia
pipelines. Is gst-omx the way forward?
Let the discussion continue...
I'll try to summarize here my perspective from a GStreamer point of
view. You wanted some, here it is :) This is a summary to answering
everything in this mail thread at this time. You can go straight to the
last paragraphs for a summary.
The question to be asked, imho, is not omx or v4l2 or gstreamer, but
rather What purpose does each of those API/interface serve, when do
they make sense, and how can they interact in the most efficient way
possible
Looking at the bigger picture, the end goal to all of us is to make
best usage of what hardware/IP/silica is available all the way up to
end-user applications/use-cases, and do so in the most efficient way
possible (whether in terms of memory/cpu/power usage at the lower
levels, but also in terms of manpower and flexibility at the higher
levels).
Will GStreamer be as cpu/memory efficient as a pure OMX solution ? No,
I seriously doubt we'll break down all the fundamental notions in
GStreamer to make it use 0 cpu when running some processing.
Can GStreamer provide higher flexibility than a pure OMX solution ?
Definitely, unless you have all the plugins for accesing all other hw
systems out there, (de)muxers, rtp (de)payloaders, jitter buffers,
network components, auto-pluggers, convenience elements, application
interaction that GStreamer has been improving over the past 10 years.
All that is far from trivial.
And as Rob Clark said that you could drop HW specific gst plugins in
and have it work with all existing applications, the same applies to all
the other peripheral existing *and* future plugins you need to make a
final application. So there you benefit from all the work done from the
non-hw-centric community.
Can we make GStreamer use as little cpu/overhead as possible without
breaking the fundamental concepts it provides ? Definitely.
There are quite a few examples out there of zero-memcpy gst plugins
wrapping hw accelerated systems for a ridiculous amount of cpu (they
just take a opaque buffer and pass it down. That's 300-500 cpu
instructions for a properly configured setup if my memory serves me
right). And efforts have been going on for the past 2 years to carry on
to make GStreamer overall consume as little cpu as possible, making it
as lockless as possible and so forth. The undergoing GStreamer 0.11/1.0
effort will allow breaking down even more barriers for even more
efficient usage.
Can OMX provide a better interface than v4l2 for video sources ?
Possible, but doubtful, The V4L2 people have been working at it for ages
and works for a *lot* of devices out there. It is the interface one
expects to use on Linux based systems, you write your kernel drivers
with a v4l2 interface and people can use it straight away on any linux
setup.
Do Hardware/Silica vendors want to write kernel/userspace drivers for
their hw-accelerated codecs in all variants available out there ? No
way, they've got better things to do, they need to chose one.
Is OMX the best API out there for providing hw-accelerated codecs ?
Not in my opinion. Efforts like libva/vdpau are better in that regards,
but for most ARM SoC ... OMX is the closest thing to a '''standard'''.
And they (Khronos) don't even provide reference implementations, so you
end up with a bunch of header files that everybody {mis|ab}uses.
So where does this leave us ?
* OMX is here for HW-accelerated codecs and vendors are doubtfully
going to switch from it, but there are other system popping up that will
use other APIs (libva, vdpau, ...).
* V4L2 has an long standing and evolving interface people expect for
video sources on linux-based systems. Making OMX provide an
as-robust/tested interface as that is going to be hard.
*
Re: [st-ericsson] v4l2 vs omx for camera
On Thu, 2011-02-24 at 21:19 +0100, Edward Hervey wrote: Will GStreamer be as cpu/memory efficient as a pure OMX solution ? No, I seriously doubt we'll break down all the fundamental notions in GStreamer to make it use 0 cpu when running some processing. I blame late night mails... I meant Will GStreamer be capable of zero-cpu usage like OMX is capable in some situation. The answer still stands. But regarding memory usage, GStreamer can do zero-memcpy provided the underlying layers have a mechanism it can use. Edward -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
On Thu, Feb 24, 2011 at 7:10 AM, Laurent Pinchart laurent.pinch...@ideasonboard.com wrote: On Thursday 24 February 2011 14:04:19 Hans Verkuil wrote: On Thursday, February 24, 2011 13:29:56 Linus Walleij wrote: 2011/2/23 Sachin Gupta sachin.gu...@linaro.org: The imaging coprocessor in today's platforms have a general purpose DSP attached to it I have seen some work being done to use this DSP for graphics/audio processing in case the camera use case is not being tried or also if the camera usecases does not consume the full bandwidth of this dsp.I am not sure how v4l2 would fit in such an architecture, Earlier in this thread I discussed TI:s DSPbridge. In drivers/staging/tidspbridge http://omappedia.org/wiki/DSPBridge_Project you find the TI hackers happy at work with providing a DSP accelerator subsystem. Isn't it possible for a V4L2 component to use this interface (or something more evolved, generic) as backend for assorted DSP offloading? So using one kernel framework does not exclude using another one at the same time. Whereas something like DSPbridge will load firmware into DSP accelerators and provide control/datapath for that, this can in turn be used by some camera or codec which in turn presents a V4L2 or ALSA interface. Yes, something along those lines can be done. While normally V4L2 talks to hardware it is perfectly fine to talk to a DSP instead. The hardest part will be to identify the missing V4L2 API pieces and design and add them. I don't think the actual driver code will be particularly hard. It should be nothing more than a thin front-end for the DSP. Of course, that's just theory at the moment :-) The problem is that someone has to do the actual work for the initial driver. And I expect that it will be a substantial amount of work. Future drivers should be *much* easier, though. A good argument for doing this work is that this API can hide which parts of the video subsystem are hardware and which are software. The application really doesn't care how it is organized. What is done in hardware on one SoC might be done on a DSP instead on another SoC. But the end result is pretty much the same. I think the biggest issue we will have here is that part of the inter- processors communication stack lives in userspace in most recent SoCs (OMAP4 comes to mind for instance). This will make implementing a V4L2 driver that relies on IPC difficult. It's probably time to start seriously thinking about userspace drivers/librairies/middlewares/frameworks/whatever, at least to clearly tell chip vendors what the Linux community expects. I suspect more of the IPC framework needs to move down to the kernel.. this is the only way I can see to move the virt-phys address translation to a trusted layer. I'm not sure how others would feel about pushing more if the IPC stack down to the kernel, but at least it would make it easier for a v4l2 driver to leverage the coprocessors.. BR, -R -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
On Thu, Feb 24, 2011 at 2:19 PM, Edward Hervey bilb...@gmail.com wrote: What *needs* to be solved is an API for data allocation/passing at the kernel level which v4l2,omx,X,GL,vdpau,vaapi,... can use and that userspace (like GStreamer) can pass around, monitor and know about. yes yes yes yes!! vaapi/vdpau is half way there, as they cover sharing buffers with X/GL.. but sadly they ignore camera. There are a few other inconveniences with vaapi and possibly vdpau.. at least we'd prefer to have an API the covered decoding config data like SPS/PPS and not just slice data since config data NALU's are already decoded by our accelerators.. That is a *massive* challenge on its own. The choice of using GStreamer or not ... is what you want to do once that challenge is solved. Regards, Edward P.S. GStreamer for Android already works : http://www.elinux.org/images/a/a4/Android_and_Gstreamer.ppt yeah, I'm aware of that.. someone please convince google to pick it up and drop stagefright so we can only worry about a single framework between android and linux (and then I look forward to playing with pitivi on an android phone :-)) BR, -R ___ gstreamer-devel mailing list gstreamer-de...@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
On Thu, Feb 24, 2011 at 7:17 AM, Hans Verkuil hverk...@xs4all.nl wrote: There are two parts to this: first of all you need a way to allocate large buffers. The CMA patch series is available (but not yet merged) that does this. I'm not sure of the latest status of this series. The other part is that everyone can use and share these buffers. There isn't anything for this yet. We have discussed this in the past and we need something generic for this that all subsystems can use. It's not a good idea to tie this to any specific framework like GEM. Instead any subsystem should be able to use the same subsystem-independent buffer pool API. yeah, doesn't need to be GEM.. but should at least inter-operate so we can share buffers with the display/gpu.. [snip] But maybe it would be nice to have a way to have sensor driver on the linux side, pipelined with hw and imaging drivers on a co-processor for various algorithms and filters with configuration all exposed to userspace thru MCF.. I'm not immediately sure how this would work, but it sounds nice at least ;-) MCF? What does that stand for? sorry, v4l2 media controller framework BR, -R -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [st-ericsson] v4l2 vs omx for camera
On Fri, Feb 18, 2011 at 10:39 AM, Robert Fekete robert.fek...@linaro.org wrote: Hi, In order to expand this knowledge outside of Linaro I took the Liberty of inviting both linux-media@vger.kernel.org and gstreamer-de...@lists.freedesktop.org. For any newcomer I really recommend to do some catch-up reading on http://lists.linaro.org/pipermail/linaro-dev/2011-February/thread.html (v4l2 vs omx for camera thread) before making any comments. And sign up for Linaro-dev while you are at it :-) To make a long story short: Different vendors provide custom OpenMax solutions for say Camera/ISP. In the Linux eco-system there is V4L2 doing much of this work already and is evolving with mediacontroller as well. Then there is the integration in Gstreamer...Which solution is the best way forward. Current discussions so far puts V4L2 greatly in favor of OMX. Please have in mind that OpenMAX as a concept is more like GStreamer in many senses. The question is whether Camera drivers should have OMX or V4L2 as the driver front end? This may perhaps apply to video codecs as well. Then there is how to in best of ways make use of this in GStreamer in order to achieve no copy highly efficient multimedia pipelines. Is gst-omx the way forward? just fwiw, there were some patches to make v4l2src work with userptr buffers in case the camera has an mmu and can handle any random non-physically-contiguous buffer.. so there is in theory no reason why a gst capture pipeline could not be zero copy and capture directly into buffers allocated from the display Certainly a more general way to allocate buffers that any of the hw blocks (display, imaging, video encoders/decoders, 3d/2d hw, etc) could use, and possibly share across-process for some zero copy DRI style rendering, would be nice. Perhaps V4L2_MEMORY_GEM? Let the discussion continue... On 17 February 2011 14:48, Laurent Pinchart laurent.pinch...@ideasonboard.com wrote: On Thursday 10 February 2011 08:47:15 Hans Verkuil wrote: On Thursday, February 10, 2011 08:17:31 Linus Walleij wrote: On Wed, Feb 9, 2011 at 8:44 PM, Harald Gustafsson wrote: OMX main purpose is to handle multimedia hardware and offer an interface to that HW that looks identical indenpendent of the vendor delivering that hardware, much like the v4l2 or USB subsystems tries to do. And yes optimally it should be implemented in drivers/omx in Linux and a user space library on top of that. Thanks for clarifying this part, it was unclear to me. The reason being that it seems OMX does not imply userspace/kernelspace separation, and I was thinking more of it as a userspace lib. Now my understanding is that if e.g. OpenMAX defines a certain data structure, say for a PCM frame or whatever, then that exact struct is supposed to be used by the kernelspace/userspace interface, and defined in the include file exported by the kernel. It might be that some alignment also needs to be made between 4vl2 and other OS's implementation, to ease developing drivers for many OSs (sorry I don't know these details, but you ST-E guys should know). The basic conflict I would say is that Linux has its own API+ABI, which is defined by V4L and ALSA through a community process without much thought about any existing standard APIs. (In some cases also predating them.) By the way IL is about to finalize version 1.2 of OpenMAX IL which is more than a years work of aligning all vendors and fixing unclear and buggy parts. I suspect that the basic problem with Khronos OpenMAX right now is how to handle communities - for example the X consortium had something like the same problem a while back, only member companies could partake in the standard process, and they need of course to pay an upfront fee for that, and the majority of these companies didn't exactly send Linux community members to the meetings. And now all the companies who took part in OpenMAX somehow end up having to do a lot of upfront community work if they want to drive the API:s in a certain direction, discuss it again with the V4L and ALSA maintainers and so on. Which takes a lot of time and patience with uncertain outcome, since this process is autonomous from Khronos. Nobody seems to be doing this, I javen't seen a single patch aimed at trying to unify the APIs so far. I don't know if it'd be welcome. This coupled with strict delivery deadlines and a marketing will to state conformance to OpenMAX of course leads companies into solutions breaking the Linux kernelspace API to be able to present this. From my experience with OMX, one of the issues is that companies usually extend the API to fullfill their platform's needs, without going through any standardization process. Coupled with the lack of open and free reference implementation and test tools, this
