Re: Beagleboard and Panda Board Drivers
Hi, On Sun, Aug 17, 2014 at 3:45 AM, Nick Krause xerofo...@gmail.com wrote: I would like to read the code for these drivers and am not sure where the code for them is. If someone can send me the directory that would be great as I am not sure where the code is. Rather than just dropping a mail if you would have googled it you would have found the required answers which you wanted. [1] http://beagleboard.org/linux [2] http://pandaboard.org/content/resources/home Regards, --Prabhakar ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Problems with Linux next tree
Hi Lucas, On Mon, Jul 14, 2014 at 9:57 PM, Lucas Tanure tan...@linux.com wrote: Hi, No I didn't. It is a clean linux-next tree. Turns out that if I don't update every day I got this issue. So, no solution yet. If it is a clean then just try $ git clean -fxd $ git pull Thanks, --Prabhakar Lad ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Problems with Linux next tree
Hi, On Tue, Jul 15, 2014 at 5:52 AM, 黄钦佳 kinkabr...@gmail.com wrote: Due to the way the linux-next tree is built, 'git pull' won't work. You want to 'git clone' Linus's master tree, then 'git remote add' the Linux-next tree. Then use 'git remote update' instead of 'git pull' when you want to refresh the tree. I use 'git remote update', and then try 'git checkout master', it tells that my branch has diverged. But I do not have modifies on that branch. So I have to try 'git reset 20140707', and then checkout successed. I don't know why, any help? You should always create your own local branch and never work on master branch! Thanks, --Prabhakar Lad ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Problems with Linux next tree
Hi Lucas, On Mon, Jul 14, 2014 at 9:07 PM, Lucas Tanure tan...@linux.com wrote: Hi, My local clone of linux-tree always fails to update. When I run git pull origin master, I got a : Automatic merge failed; fix conflicts and then commit the result. Form the above message looks like you have done some modifications to your branch which is conflicting with the git pull. So, How I can keep my local tree updated ? No matter what. so you have to create a patch of your modifications reset the HEAD and then do a git pull and then later apply your patch. Thanks, --Prabhakar Lad ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: How to use .dts file for Kernel Image Compilation
Hi, On Wed, Jan 22, 2014 at 3:41 PM, sanchayan maity victorascr...@gmail.com wrote: Hello Everyone, I am compiling kernel image for a Toradex Colibri module which uses the NVidia Tegra2 processor. The device tree support and files are supplied, which i can see on the below link. http://lxr.free-electrons.com/source/arch/arm/boot/dts/?a=arm The file name is tegra20-iris-512.dts which then includes tegra20-colibri-512.dtsi. I want to know how can i link this while doing make for kernel image compilation. This is required as board config file is not present and the device tree has to be used. Based on my current findings, if the file name is for example exynos4.dts, this will be specified in the config file with CONFIG_MACH_EXYNOS4_DT=y. I want to know if this is the correct way of specifying a device tree file for which .dtb has been generated? The kernel version for which i am trying to do this is 3.12.6. If your configuration supports (defconfig) DT booting for your platform you can build .dtb by just replacing the uImage to dtbs in the command what you used for building the uImage. Note:- For DT booting there should be also support in the U-Boot. Regards, --Prabhakar Lad http://in.linkedin.com/in/prabhakarlad ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: kernel driver access application memory
Hi, On Wed, Jan 15, 2014 at 11:45 PM, m silverstri michael.j.silvers...@gmail.com wrote: Hi, If my application allocate memory for input and output buffers, and pass the pointer to a kernel driver (via v4l2 queue buffer operation), can the kernel driver access it? Do I need to setup DMA before teh kernel driver can read/write to it? If your application is allocating memory for v4l2 buffers how are you making sure its contiguous ? What call are you using to allocate memory @application level ? If the application is allocating buffers its USER_PTR buffer. Yes kernel can access the buffer. For reading and writing of buffers you dont need to setup DMA. Regards, --Prabhakar Lad http://in.linkedin.com/in/prabhakarlad ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: How to enable VIDEOBUF2_VMALLOC
Hi, On Thu, Jan 16, 2014 at 5:45 AM, m silverstri michael.j.silvers...@gmail.com wrote: Hi, How can I enable VIDEOBUF2_VMALLOC? I try 'make menuconfig', but I don't know how can I configure to enable VIDEOBUF2_VMALLOC: The videobuf2 supports 3 types of buffer: 1: VIDEOBUF2_DMA_CONTIG 2: VIDEOBUF2_DMA_SG 3: VIDEOBUF2_VMALLOC It all depends on your hardware (bridge driver) which supports this So if your bridge driver supports say VIDEOBUF2_VMALLOC then in your Kconfig for the bridge driver you need to add the following line select VIDEOBUF2_VMALLOC so this will be built along your driver. Hope this helps! Thanks, --Prabhakar Lad https://www.linkedin.com/in/prabhakarlad Symbol: VIDEOBUF2_VMALLOC [=n] │ Type : tristate │ Defined at drivers/media/v4l2-core/Kconfig:75 │ Depends on: MEDIA_SUPPORT [=y] │ Selects: VIDEOBUF2_CORE [=y] VIDEOBUF2_MEMOPS [=n] DMA_SHARED_BUFFER [=y] │ Selected by: USB_VIDEO_CLASS [=n] USB [=y] MEDIA_SUPPORT [=y] MEDIA_USB_SUPPORT [=n] MEDIA_CAMERA_SUPPORT [=y] || USB_PWC [=n] USB [=y] MEDIA_SUPPORT [=y] MEDIA_USB_SUPPORT [=n] MEDIA_CAMERA_SUPPORT [=y] VIDEO_V4L2 [=y] || VIDEO_STK1160 [=n] USB [=y] MEDIA_SUPPORT [=y] MEDIA_USB_SUPPORT [=n] MEDIA_ANALOG_TV_SUPPORT [=n] VIDEO_DEV [=y] I2C [=y] || VIDEO_EM28XX [=n] USB [=y] MEDIA_SUPPORT [=y] MEDIA_USB_SUPPORT [=n] (MEDIA_CAMERA_SUPPORT [=y] Thank you. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: issue with compiling kernel module
Hi Arun, On Sat, Jan 11, 2014 at 9:03 AM, Arun M Kumar arunkr.li...@gmail.com wrote: I am facing the following error message when i try to compile my kernel module. it is a simple hello world module make: Entering directory `/usr/src/linux-3.4.6-2.10' ERROR: Kernel configuration is invalid. include/generated/autoconf.h or include/config/auto.conf are missing. Run 'make oldconfig make prepare' on kernel src to fix it. make: *** No rule to make target `Device'. Stop. make: Leaving directory `/usr/src/linux-3.4.6-2.10' I have tried the said option, of make oldconfig and prepare... I even recompiled the source using defconfig and am using that kernel, but still i get this error. Please help. Need more info on this to help.. 1: Is your module part of kernel source tree or Independent ? 2: How you makefile looks ? Thanks, --Prabhakar Lad https://www.linkedin.com/in/prabhakarlad ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: ARM Linux and ATAGS
Hi, On Thu, Jan 9, 2014 at 1:17 PM, Mj Embd mj.e...@gmail.com wrote: Hi, What are atags and are they still used after addition of device tree in linux ? Refer [1] for more info on atags, and refer [2] for your second question. [1] http://www.simtec.co.uk/products/SWLINUX/files/booting_article.html [2] http://elinux.org/Device_Tree Regards, --Prabhakar Lad http://in.linkedin.com/in/prabhakarlad ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: What to do with branches after submitting patches?
Hi Matthias, On Fri, Oct 11, 2013 at 3:53 AM, Matthias Beyer m...@beyermatthias.de wrote: Hi, I just got into kernel development and currently doing some patching of the usb divers for coding style adaptions and so on. My current workflow is: - get latest torvalds master - merge local master with fast forward to torvalds/master - create new branch, say usb-core-foobar-cleanup - patch the stuff, write commits - git format-patch master...usb-core-foobar-cleanup - git send-email ... So what to do with the branches now? I think I should keep them until the patches are merged, okay. And then? delete them? I mean, I'm still the author of the patches, and they will be included in history some time (as soon as the next release comes out they will be in torvalds/master). Yeah looks ok but , what you can do is USB is subsystem it should be maintained by some person, which he has his own repo somewhere in kernel.org clone his repo and do what your changes what you meant and send the patches via send-email. You need to maintain your branch until your patches are accepted because there might be some review comments so you got to fix them and repost the patches. You can also create your own repo on github and push that branch until then. I just submitted my second patch series to the lkml, and now I have to remember which patch series was the result of which branch... if I submit one or two more patch series, I have to remember the relations between patch series and branches until they are merged, yeah? Yes Or is there something wrong in my workflow? Is it possible to use a github repository and just send a please pull from g...@github.com message to the kernel mailinglist, or will I be beaten for this? You cannot directly send a pull request until the patches are reviewed, once the the driver maintainer and other folks in the ML are happy, the maintainer will pull your patches and get it merged in mainline kernel. Regards, --Prabhakar Lad ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: What to do with branches after submitting patches?
On Fri, Oct 11, 2013 at 3:55 PM, Prabhakar Lad prabhakar.cse...@gmail.com wrote: On Fri, Oct 11, 2013 at 3:34 PM, Mandeep Sandhu mandeepsandhu@gmail.com wrote: Is it possible to use a github repository and just send a please pull from g...@github.com message to the kernel mailinglist, or will I be beaten for this? You cannot directly send a pull request until the patches are reviewed, once the the driver maintainer and other folks in the ML are happy, the maintainer will pull your patches and get it merged in mainline kernel. If using github, I think send pull requests is a way to initiate a review. It does not mean that that pull request will be merged as-is. As you point out, if there are review comments, the reviewee will address those comments and send another pull request till the reviewer is satisfied. After that the reviewer just has to 'merge' the latest pull request. For reviewing patches on the mailing list you don't send pull request, ! patches needs to be sent to ML to be reviewed !. For example look at [1] which is pull request to Linus. The pull request will just have the patch description(it doesnt have the diff), and the link to pull the patches from. People dont have time to go to your link and review the patches there and reply on your pull request. So you need to send patches to ML for review and not pull request Ahh missed the link. [1] http://lkml.indiana.edu/hypermail/linux/kernel/1307.0/02639.html Thanks, --Prabhakar Lad ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: What to do with branches after submitting patches?
On Fri, Oct 11, 2013 at 3:34 PM, Mandeep Sandhu mandeepsandhu@gmail.com wrote: Is it possible to use a github repository and just send a please pull from g...@github.com message to the kernel mailinglist, or will I be beaten for this? You cannot directly send a pull request until the patches are reviewed, once the the driver maintainer and other folks in the ML are happy, the maintainer will pull your patches and get it merged in mainline kernel. If using github, I think send pull requests is a way to initiate a review. It does not mean that that pull request will be merged as-is. As you point out, if there are review comments, the reviewee will address those comments and send another pull request till the reviewer is satisfied. After that the reviewer just has to 'merge' the latest pull request. For reviewing patches on the mailing list you don't send pull request, ! patches needs to be sent to ML to be reviewed !. For example look at [1] which is pull request to Linus. The pull request will just have the patch description(it doesnt have the diff), and the link to pull the patches from. People dont have time to go to your link and review the patches there and reply on your pull request. So you need to send patches to ML for review and not pull request Thanks, --Prabhakar Lad ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Several unrelated beginner questions.
Hi Konstantin, On Thu, Mar 7, 2013 at 4:49 AM, Konstantin Kowalski kostya-...@mail.ru wrote: Hello everyone, I am interested in Linux kernel programming (and OS kernels and general), and I am currently reading several books about Linux kernel. I have a few questions about it: 1.) Currently, I am reading 2 books about Linux kernel: Linux Device Drivers (3rd edition) and Linux Kernel Development (3rd edition). I like both books and I am learning a lot from them. I heard that both of this books are outdated, but so far all the information in this books seems valid and applicable. Is there better books you would recommend? I think you go ahead with above books only. 2.) In Linux Device Drivers, it states that module_exit(function) is discarded if module is built directly into kernel or if kernel is compiled with option to disallow loadable modules. But what if the module still has to do something during shutdown? Releasing memory is unimportant since it does not persist over reboot, but what if the module has to write something to a disk file, or do some other action? Linux is OS, If not that way there are alternatives, what you can do is use register_reboot_notifier() call, which arranges to call code blocks when sys_reboot() is called. 3.) What's the deal with different kernel versions? I heard back in the 2.x days, even kernels were stable and odd versions were experimental, but with 2.6 it changed. 'different kernel versions' means after each release of Linux it has version. like as you mentioned 2.6 above. Currently the naming convention is as follows the number was composed as A.B.C, where the number A denoted the kernel version, the number B denoted the major revision of the kernel, and the number C indicated the minor revision of the kernel. So with 3.x kernels, are all of them experimental in the beginning and stable in the end? Also, with 3.x new versions seem to be released more often than in 2.1-2.5 days. Did the release cycle get smaller or is it just my imagination? Also, what does rc number mean? Stable kernel release depends on Linus/Greg etc.. Which involves lots of work for them :). No The release cycle is 2-3 months. 4.) Currently, I am running linux-next, and it works great. Am I correct to assume that linux-next is supposed to have newest, shiniest and most unstable features? `uname -a` says that I am still running 3.8-next, but there is already 3.9 out. So which version is more experimental and least stable? Which one is the newest? The linux-next tree to serve as a place where patches aimed to be merged during the next development cycle are gathered. The newest one is 3.9.rc1 which is the release candidate. The release candidate usually have patches for bug fixes no new feature or drivers add up here. 5.) How exactly does make/.config work? When I run `make oldconfig`, does it use the everything from the previous .config and only ask how to configure new features? And when I run `make` does it re-use old object files if nothing was changed in the specific file, or does it re-compile everything from scratch? when you do `make oldconfig' 'It reads the existing .config file and prompts the user for options in the current kernel source that are not found in the file. This is useful when taking an existing configuration and moving it to a new kernel. make program is an intelligent utility and works based on the changes you do in your source files. If you have four files main.cpp, hello.cpp, factorial.cpp and functions.h. Here all the remaining files are dependent on functions.h and main.cpp is dependent on hello.cpp and factorial.cpp. So if you make any change in functions.h then make will recompile all the source files to generate new object files. But if you make any change main.cpp, as this is not dependent of any other fil, then in this case only main.cpp file will be recompiled and hellp.cpp and factorial.cpp will not be recompiled. While compiling a file, make checks its object file and compare the time staps, if source file has newer time stamp than object file then it will generate new object file assuming that source file has been changed. Regards, --Prabhakar Lad http://in.linkedin.com/pub/prabhakar-lad/19/92b/955 Thank you, Kostyantyn Kovalskyy (Konstantin Kowalski) ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Regarding GPIO driver module
Hi, On Wed, Mar 6, 2013 at 12:23 PM, Rajesh Bhaskaran cb.rajesh...@gmail.com wrote: Hi all , I was trying to write a GPIO driver module for Hawkboard , in order to toggle the LEDs connected to the GPIOs . I am using a OMAP L138 processor , and am trying to do a ioremap of the physical address space to the Kernel's virtual address space . But I guess I am not able to figure out the exact base address of the GPIO bank . I am basically trying to toggle the GPIO Bank 6 . I went through the OMAP L138 reference manual , but am unable to find the base address . Afterwards I plan to use the ioctl function to toggle the LEDs . Attaching herewith the link to the OMAP L138 reference manual . Reference manual : www.ti.com/lit/ug/spruh77a/spruh77a.pdf Could anyone kindly guide me , on the procedure to decipher the Baseaddress of the GPIO Bank 6 from the Reference manual ? You need to go through the memory map of the device refer[1] for this. In [1] refer table 2-4 you will find the entire memory map including GPIO. For GPIO refer this [2] too. Regards, --Prabhakar Lad http://in.linkedin.com/pub/prabhakar-lad/19/92b/955 [1] http://www.ti.com/lit/ds/sprs586d/sprs586d.pdf [2] http://www.ti.com/lit/ug/sprufl8b/sprufl8b.pdf Thanks in advance ! Cheers , ~RCB~ ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re:
Hi,
On Mon, Feb 25, 2013 at 12:54 PM, Prasad Lakshman
prasad.bl@gmail.com wrote:
Hi ,
I am trying to implement own system call in Linux. Kernel version I
chose is 3.5.7
I am following the steps from Linux Kernel Development 3rd edition.
I got two problems with the implementation.
1.while trying to modify the code in kernel , there is no entry.S file
for Intel x86 32 bit architecture. (my be i am missing some thing.)
2.while I am compiling user application with gcc I am getting
Things have slightly changed in the newer kernel version
you can refer the below links,
https://bbs.archlinux.org/viewtopic.php?id=144772
http://blog.techveda.org/index.php/adding-system-calls-linux-kernel-3-5-x/
Regards,
--Prabhakar Lad
http://in.linkedin.com/pub/prabhakar-lad/19/92b/955
error: unknown type name ‘helloworld’
my application is as follows
#define __NR_helloworld 367
__syscall0(long, helloworld)
int main ()
{
printf(The helloworld system call is\n;
helloworld();
return 0;
}
I looked at Link [blog.163.com] which is given by Wanny but i could
not find the solution,I could not locate syscall_table_32.s in my
Linux source.
Please help me in identifying the entry.S file for Intel x86 32 bit
architecture in 3.5.7 kernel version sources,where i can make an entry
for my system call into system call table.
Help me in resolving error: unknown type name ‘helloworld’ in my application.
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Re: How controll is passed from uboot to kernel
Hi, On Sat, Feb 16, 2013 at 10:13 AM, Chetan C.R. chetan...@gmail.com wrote: Hi All, I need to know how the control is passed from u-boot to kernel in Linux operating system Refer this link http://www.simtec.co.uk/products/SWLINUX/files/booting_article.html for booting ARM. Regards, --Prabhakar http://www.linkedin.com/pub/prabhakar-lad/19/92b/955 Thanks in Advannce ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: 8250 UART doesn't populate /proc/iomem?
Hi Woody, On Mon, Dec 10, 2012 at 11:54 AM, Woody Wu narkewo...@gmail.com wrote: Hi, list I found some io memory information is lost from /dev/iomem and want to find out why. I have a 2.6.16 kernel running on a ARM board (Samsung S3C2410). From the kernel log, I see 16 8250 serial ports were detected, and each of thoese ports has a memory address: [Snip] You see, there is no serial8250 informations. Can anyone here please tell me how this can happen? Does it mean the serial8250 driver don't populate or register in the /proc/iomem? Can you look at the o/p of /proc/ioports and see if the entry is present here. Regards, --Prabhakar Lad -- woody I can't go back to yesterday - because I was a different person then. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: double exclamation mark meaning ?
Hi, On Thu, Dec 6, 2012 at 3:20 PM, Shraddha Kamat sh200...@gmail.com wrote: Hi, # define likely(x) __builtin_expect(!!(x), 1) # define unlikely(x)__builtin_expect(!!(x), 0) I see these !! in the above expressions. Please explain me the meaning of those double exclamations. What is their significance ? The Operator ! is used to perform the Boolean operation NOT. For example: !(1) --- Outputs to 0 (false). !(2.56565) --- Outputs to 0 (false). !(20) Outputs to 0 (false). !(-123)--- Outputs to 0 (false). !(0)- Outputs to 1 (true). Similarly '!!' Performs twice NOT operation !!(1) --- Outputs to 1 (true). !!(2.56565) --- Outputs to 1 (true). !!(20) Outputs to 1 (true). !!(-123)--- Outputs to 1 (true). !!(0)- Outputs to 0 (false). Hope that clears your doubt. Regards, --Prabhakar Lad -- Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: MAX_ORDER in mmzone.h
Hi, On Mon, Aug 27, 2012 at 8:00 AM, J.Hwan Kim frog1...@gmail.com wrote: Hi, everyone I wish to expand the limit for allocating contiguous memory in kernel. So, if I change the value CONFIG_FORCE_MAX_ZONEORDER or MAX_ORDER value in /include/linux/mmzone.h, will it cause any problem or side effect in x86_64 sysem? Recently Contiguous memory allocator got merged into 3.5 Kernel you can use the same to declare as much contiguous memory needed. Thx, --Prabhakar Lad http://www.linkedin.com/profile/view?id=65006993trk=tab_pro Thanks in advance. Best Regards, J.Hwan Kim ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: resubmitting patches
Hi Christopher, If your patches are still not accepted, then you can send a new series with version number(V2), and what all you changed from the previous version. Regards, --Prabhakar Lad On Wed, Mar 28, 2012 at 8:59 PM, Christopher Harvey ch...@basementcode.com wrote: If I have patches sent to a kernel mailing list that are still under review and want to add more, should I resend the whole series with the new ones or should I only send the new patches as a new thread? ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: linux camera drivers
Mayank, On Sat, Mar 3, 2012 at 9:51 AM, Mayank Agarwal mayank77fromin...@gmail.comwrote: On Fri, Mar 2, 2012 at 10:08 AM, Mayank Agarwal mayank77fromin...@gmail.com wrote: 1.I think the device supports i2c or spi protocol.I want to know how the i2c or spi is taking data from image sensor and giving it to video buffers. Most of the cameras support i2c or csi. 2.I want to understand the whole data flow from image sensor to the display buffer and the role of linux kernel camera drivers in that. For this you need to understand the V4L2 Framework, Or later Media Controller Framework. 3.Currently i am looking at Sony IMX036,Aptima MT9P031. You can find in directory source/drivers/media/video/ MT9p031 support is there in current kernel but no idea about imx036. Regards, ---Prabhakar Lad Mob: +91-9611756433 http://in.linkedin.com/pub/prabhakar-lad/19/92b/955 Thanks and Regards, Mayank On Thu, Mar 1, 2012 at 8:22 PM, Greg KH g...@kroah.com wrote: On Thu, Mar 01, 2012 at 05:57:52PM +0530, Mayank Agarwal wrote: Hi all, I have following questions regarding camera drivers in linux kernel. 1.which are the files/folder in kernel directory where camera drivers support is provided in linux kernel. It depends, which type of protocol does your device support? 2.Are they customisable according to different SOC requirements. It depends on what the requirements are. As it's software, it's always able to be changed :) 3.Are there any tutorials/pdfs to understand camera drivers in linux kernel. What is wrong with the code itself? 4.At present which sensor (i mean aptina/sony/omnivision) drivers are supported in linux kernel. What sensor are you looking for exactly? What device do you need to support, and what protocol does your camera use to talk to the hardware? greg k-h ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
How to avoid volatiles
Hi everyone, I had question in want eradicate volatile from here: for example: #define 0x01c40800 if ((volatile void *)pllbase == (volatile void *)DAVINCI_PLL_CNTRL0_BASE) /**HERE**/ return 8; else return pll_div(pllbase, PLLC_PREDIV); Thanks. Regards --Prabhakar ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: How to avoid volatiles
Thanks Rohan. Regards --Prabhakar On Fri, Oct 14, 2011 at 3:14 PM, rohan puri rohan.pur...@gmail.com wrote: On Fri, Oct 14, 2011 at 2:51 PM, Prabhakar Lad prabhakar.cse...@gmail.com wrote: Hi everyone, I had question in want eradicate volatile from here: for example: #define 0x01c40800 if ((volatile void *)pllbase == (volatile void *)DAVINCI_PLL_CNTRL0_BASE) /**HERE**/ return 8; else return pll_div(pllbase, PLLC_PREDIV); Thanks. Regards --Prabhakar ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies Hi, volatile keyword is make use of to enforce compiler that not to optimize the code that contains this qualifier. In this case maybe any of the two compared values could be changed in an unknowing way to the compiler which are to be considered and no optimization is required, hence volatile keyword is made use of. Regards, Rohan Puri ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: How to avoid volatiles
Hi, Yes even though its a movement checkpatch doesn't consider it ;) . Regards --Prabhakar On Fri, Oct 14, 2011 at 3:49 PM, Srivatsa Bhat bhat.sriva...@gmail.comwrote: On Fri, Oct 14, 2011 at 3:39 PM, Srivatsa Bhat bhat.sriva...@gmail.comwrote: Forwarding to kernelnewbies list.. -- Forwarded message -- From: Prabhakar Lad prabhakar.cse...@gmail.com Date: Fri, Oct 14, 2011 at 3:35 PM Subject: Re: How to avoid volatiles To: Srivatsa Bhat bhat.sriva...@gmail.com Hi, here you go Patch http://patchwork.ozlabs.org/patch/115134/ Regards --Prabhakar Hmm.. from what I see, the warnings are due to use of volatile keyword, but the code already existed in the kernel and you just moved it to another file.. Regards, Srivatsa S. Bhat ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
