Re: How can I find out what is the driver for device node '/dev/video11'
Sylwester, Devin, Thank you. On Wed, Jan 8, 2014 at 1:19 PM, Sylwester Nawrocki wrote: > On 01/08/2014 08:15 PM, m silverstri wrote: >> >> Thanks. >> >> I am studying android source code. >> From here, it has code which open("/dev/video11", O_RDWR, 0) as >> decoding device. >> >> >> http://androidxref.com/4.4.2_r1/xref/hardware/samsung_slsi/exynos5/libhwjpeg/ExynosJpegBase.cpp > > > What you're looking for might be this proprietary Samsung JPEG codec driver > used in Android. > > https://android.googlesource.com/kernel/exynos/+/android-exynos-3.4/drivers/media/video/exynos/jpeg/ > > If you intend to use mainline kernel you need to consider the s5p-jpeg > driver, > which exposes to user space standard interface without any proprietary > additions > incompatible with the V4L2 spec. > > >> I want to find out which is the corresponding driver code for device >> '/dev/video11'. > > > I suspect these numbers are fixed in the Android kernel (they are hard > coded in the user space library as you're pointing out above), which is > a pretty bad practice. > > It's better to use VIDIOC_QUERYCAP ioctl to find a video device with > specific name, as Devin suggested. You can also find a video device > exposed by a specific driver through sysfs, as is done in > exynos_v4l2_open_devname() function in this a bit less hacky code: > > https://android.googlesource.com/platform/hardware/samsung_slsi/exynos5/+/jb-mr1-release/libv4l2/exynos_v4l2.c > > Thanks, > Sylwester -- 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: How can I find out what is the driver for device node '/dev/video11'
On 01/08/2014 08:15 PM, m silverstri wrote: Thanks. I am studying android source code. From here, it has code which open("/dev/video11", O_RDWR, 0) as decoding device. http://androidxref.com/4.4.2_r1/xref/hardware/samsung_slsi/exynos5/libhwjpeg/ExynosJpegBase.cpp What you're looking for might be this proprietary Samsung JPEG codec driver used in Android. https://android.googlesource.com/kernel/exynos/+/android-exynos-3.4/drivers/media/video/exynos/jpeg/ If you intend to use mainline kernel you need to consider the s5p-jpeg driver, which exposes to user space standard interface without any proprietary additions incompatible with the V4L2 spec. I want to find out which is the corresponding driver code for device '/dev/video11'. I suspect these numbers are fixed in the Android kernel (they are hard coded in the user space library as you're pointing out above), which is a pretty bad practice. It's better to use VIDIOC_QUERYCAP ioctl to find a video device with specific name, as Devin suggested. You can also find a video device exposed by a specific driver through sysfs, as is done in exynos_v4l2_open_devname() function in this a bit less hacky code: https://android.googlesource.com/platform/hardware/samsung_slsi/exynos5/+/jb-mr1-release/libv4l2/exynos_v4l2.c Thanks, Sylwester -- 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: How can I find out what is the driver for device node '/dev/video11'
Thanks. I am studying android source code. >From here, it has code which open("/dev/video11", O_RDWR, 0) as decoding device. http://androidxref.com/4.4.2_r1/xref/hardware/samsung_slsi/exynos5/libhwjpeg/ExynosJpegBase.cpp I want to find out which is the corresponding driver code for device '/dev/video11'. Thank you very much. On Wed, Jan 8, 2014 at 11:08 AM, Devin Heitmueller wrote: > On Wed, Jan 8, 2014 at 2:03 PM, m silverstri > wrote: >> Thanks. I don't have the a running hardware. >> If I can only search within the code space, how can I find out which >> driver is for '/dev/video11'? >> >> Is there a config file which I can look it up? > > If you don't actually have the hardware platform, then determining it > just from the source code is a huge undertaking (unless it's some well > known device which happens to always create it at that offset). > > What is the hardware platform, and what is the capture device? > > Devin > > -- > Devin J. Heitmueller - Kernel Labs > http://www.kernellabs.com -- 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: How can I find out what is the driver for device node '/dev/video11'
On Wed, Jan 8, 2014 at 2:03 PM, m silverstri wrote: > Thanks. I don't have the a running hardware. > If I can only search within the code space, how can I find out which > driver is for '/dev/video11'? > > Is there a config file which I can look it up? If you don't actually have the hardware platform, then determining it just from the source code is a huge undertaking (unless it's some well known device which happens to always create it at that offset). What is the hardware platform, and what is the capture device? Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com -- 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: How can I find out what is the driver for device node '/dev/video11'
Thanks. I don't have the a running hardware. If I can only search within the code space, how can I find out which driver is for '/dev/video11'? Is there a config file which I can look it up? Thank you. On Wed, Jan 8, 2014 at 10:56 AM, Devin Heitmueller wrote: > On Wed, Jan 8, 2014 at 1:50 PM, m silverstri > wrote: >> In linux kernel, a device (e.g. codec) can register as a file (e.g. >> /dev/video11). >> >> How can I find out from the code which driver is registered as >> '/dev/video11'. i.e. what is the driver will be invoked when I >> open('/dev/video11', O_RDWR,0) in my user space code? >> -- >> 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 > > The QUERYCAP ioctl() will tell you the driver name. > > http://linuxtv.org/downloads/v4l-dvb-apis/vidioc-querycap.html > > Devin > > -- > Devin J. Heitmueller - Kernel Labs > http://www.kernellabs.com -- 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: How can I find out what is the driver for device node '/dev/video11'
On Wed, Jan 8, 2014 at 1:50 PM, m silverstri wrote: > In linux kernel, a device (e.g. codec) can register as a file (e.g. > /dev/video11). > > How can I find out from the code which driver is registered as > '/dev/video11'. i.e. what is the driver will be invoked when I > open('/dev/video11', O_RDWR,0) in my user space code? > -- > 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 The QUERYCAP ioctl() will tell you the driver name. http://linuxtv.org/downloads/v4l-dvb-apis/vidioc-querycap.html Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com -- 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
How can I find out what is the driver for device node '/dev/video11'
In linux kernel, a device (e.g. codec) can register as a file (e.g. /dev/video11). How can I find out from the code which driver is registered as '/dev/video11'. i.e. what is the driver will be invoked when I open('/dev/video11', O_RDWR,0) in my user space code? -- 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