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path: root/src/v4l2/v4l2_camera_proxy.cpp
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2020-06-25v4l2: v4l2_camera_proxy: Set timestamp monotonic buffer flag on reqbufsPaul Elder
Set buffer flag V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC at VIDIOC_REQBUFS after the buffers have been allocated. Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-06-25v4l2: v4l2_camera_proxy: Clear reserved field in reqbufsPaul Elder
Clear the reserved field in arg struct v4l2_reqbuffers of VIDIOC_REQBUFS. Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-06-25v4l2: v4l2_camera_proxy: Free old buffers on reqbufs > 0Paul Elder
Free buffers, if any were previously allocated, at VIDIOC_REQBUFS with count > 0. Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-06-25v4l2: v4l2_compat: Support multiple openPaul Elder
Previously, since we acquired the libcamera camera upon open(), it was impossible to support multiple open, as any subsequent opens would return error because the camera would already be acquired. To fix this, we first initialize the camera in the first call to V4L2CameraProxy::open(), just to heat up the stream format cache. We then add ownership by a V4L2CameraFile of a V4L2Camera via the V4L2CameraProxy. All vidioc ioctls prior to reqbufs > 0 (except for s_fmt) are able to access the camera without ownership. A call to reqbufs > 0 (and s_fmt) will take ownership, and the ownership will be released at reqbufs = 0. While ownership is assigned, the eventfd that should be signaled (and cleared) by V4L2Camera and V4L2CameraProxy is set to the V4L2CameraFile that has ownership, and is cleared when the ownership is released. In case close() is called without a reqbufs = 0 first, the ownership is also released on close(). We also use the V4L2CameraFile to contain all the information specific to an open instance of the file. This removes the need to keep track of such information within V4L2CameraProxy via multiple maps from int fd to info. Since V4L2 does not expect reqbufs 0 to ever return error, make V4L2CameraProxy::freeBuffers() return void. Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-06-25v4l2: V4L2CameraProxy: Take V4L2CameraFile as argument for intercepted callsPaul Elder
Prepare for using the V4L2CameraFile as a container for file-specific information in the V4L2 compatibility layer by making it a required argument for all V4L2CameraProxy calls that are directed from V4L2CompatManager, which are intercepted via LD_PRELOAD. Change V4L2CameraFile accordingly. Also change V4L2CompatManager accordingly. Instead of keeping a map of file descriptors to V4L2CameraProxy instances, we keep a map of V4L2CameraFile instances to V4L2CameraProxy instances. When the proxy methods are called, feed the file as a parameter. The dup function is also modified, in that it is removed from V4L2CameraProxy, and is handled completely in V4L2CompatManager, as a map from file descriptors to V4L2CameraFile instances. Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-06-23libcamera: Add support for planar YUV422 and YUV420 formatsDavid Plowman
These formats can be helpful when downstream applications or libraries support them natively (avoiding a costly conversion). Signed-off-by: David Plowman <david.plowman@raspberrypi.com> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: David Plowman <david.plowman@raspberrypi.com> Tested-by: David Plowman <david.plowman@raspberrypi.com> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
2020-06-19v4l2: v4l2_compat: Intercept open64, openat64, and mmap64Paul Elder
Some applications (eg. Firefox, Google Chrome, Skype) use open64, openat64, and mmap64 instead of their non-64 versions that we currently intercept. Intercept these calls as well. _LARGEFILE64_SOURCE needs to be set so that the 64-bit symbols are available and not synonymous to the non-64-bit versions on 64-bit systems. Also, since we set _FILE_OFFSET_BITS to 32 to force the various open and mmap symbols that we export to not be the 64-bit versions, our dlsym to get the original open and mmap calls will not automatically be converted to their 64-bit versions. Since we intercept both 32-bit and 64-bit versions of open and mmap, we should be using the 64-bit version to service both. Fetch the 64-bit versions of openat and mmap directly. musl defines the 64-bit symbols as macros that are equivalent to the non-64-bit symbols, so we put compile guards that check if the 64-bit symbols are defined. Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> # Compile with musl Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
2020-06-18v4l2: Replace explicit DRM FourCCs with libcamera formatsLaurent Pinchart
Use the new pixel format constants to replace usage of macros from drm_fourcc.h. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
2020-06-17v4l2: v4l2_camera_proxy, v4l2_camera: Check return values of read/writePaul Elder
The return value of the write to the eventfd (to signal POLLIN) from V4L2Camera and the read from the eventfd (to clear POLLIN) from V4L2CameraProxy was ignored. Check the return value, and print an error message. Reported-by: Coverity CID=290743 Reported-by: Coverity CID=290744 Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-06-09v4l2: v4l2_camera_proxy: Support MJPEGPaul Elder
Add an entry for MJPEG in V4L2CameraProxy's PixelFormatInfo list to allow proper calculation of sizeimage for MJPEG, such that the parameters to mmap can align properly instead of failing. This allows MJPEG to be used in the V4L2 compatibility layer. Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-06-08v4l2: v4l2_camera_proxy: Fix NV24 subsamplingKieran Bingham
The NV24 pixelFormatInfo table entry defines an incorrect horizontal sub-sampling. Update to the correct value. Fixes: 29c5508075c1 ("v4l2: camera_proxy: Create format info array") Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-06-08v4l2: v4l2_camera_proxy: Fix segfault on restarting streamsPaul Elder
The V4L2 compatibility layer keeps track of the index of the next buffer to be dequeued, to handle VIDIOC_DQBUF. This index is set to 0 on startup and incremented (modulo #frames), and is otherwise never reset. This means that if the last handled frame index is not #frames-1, and the stream is restarted without restarting libcamera and the V4L2 compatilibity layer, the buffer index number won't match with the libcamera buffer index number, causing a segfault. Fix this by resetting the current buffer index to zero on VIDIOC_STREAMON. Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
2020-06-08v4l2: v4l2_compat: Add eventfd signaling to support pollingPaul Elder
To support polling, we need to be able to signal when data is available to be read (POLLIN), as well as events (POLLPRI). Add the necessary calls to eventfd to allow signaling POLLIN. We signal POLLIN by writing writing to the eventfd, and clear it by reading from the eventfd, upon VIDIOC_DQBUF. Note that eventfd does not support signaling POLLPRI, so we don't yet support V4L2 events. Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-06-08v4l2: v4l2_camera_proxy: Don't return -EINVAL for zero sizeimage in REQBUFSPaul Elder
If VIDIOC_REQBUFS returns -EINVAL, it signals to the application that the requested buffer or memory type is not supported. If we return -EINVAL due to a zero sizeimage, then the application will think that we don't support a memory type that we actually do. We cannot error on a zero sizeimage, because reqbufs could be called merely to probe what IO methods we support; qv4l2, for example, called reqbufs once with userptr and once more with mmap, both times with count=1. On the other hand, sizeimage will be zero for formats whose size we don't know how to calculate, such as MJPEG. If we try to stream such formats anyway, we will get a floating point exception and crash. Issue a warning for now, and don't return -EINVAL, so that we can continue operation. Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-06-08v4l2: v4l2_camera_proxy: Acquire only one buffer semaphore on VIDIOC_DQBUFPaul Elder
We use a semaphore to atomically keep track of how many buffers are available for dequeueing. The check for how to acquire the semaphore was incorrect, leading to a double acquire upon a successful nonblocking acquire. Fix this. Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
2020-06-08v4l2: v4l2_camera_proxy: Fix bounds check for VIDIOC_ENUM_FMTPaul Elder
VIDIOC_ENUM_FMT is meant to return -EINVAL if the requested index is out of bounds. This bounds is obtained from the libcamera Camera's list of formats. The bounds check for this list was incorrect; fix it. Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
2020-05-28v4l2: Relicense V4L2 compatibility layer under LGPLLaurent Pinchart
The V4L2 compatibility layer is licensed under the GPL. It is compiled as a binary separate from libcamera.so, and is loaded into the address space of processes through LD_PRELOAD to intercept calls to the C library. It is our understanding and intent that the GPL license doesn't propagate to the binaries whose calls are intercepted, considering those binaries are not derivative work of the V4L2 compatibility layer and are not designed to be linked to the V4L2 compatibility layer. There is however a possibly grey area if binaries are packaged with a shell script wrapper that loads the V4L2 compatibility layer. This could lead to license-related issues if such packaging is performed by Linux distributions or system integrators. To clarify the intent and lift the doubts, relicense the V4L2 compatibility layer under the LGPL. The V4L2 compatibility layer code itself still benefits from the license protection, while its usage with third-party binaries is clearly allowed as intended. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Acked-by: Jacopo Mondi <jacopo@jmondi.org> Acked-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Acked-by: Paul Elder <paul.elder@ideasonboard.com> Acked-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Acked-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
2020-05-16libcamera: Move internal headers to include/libcamera/internal/Laurent Pinchart
The libcamera internal headers are located in src/libcamera/include/. The directory is added to the compiler headers search path with a meson include_directories() directive, and internal headers are included with (e.g. for the internal semaphore.h header) #include "semaphore.h" All was well, until libcxx decided to implement the C++20 synchronization library. The __threading_support header gained a #include <semaphore.h> to include the pthread's semaphore support. As include_directories() adds src/libcamera/include/ to the compiler search path with -I, the internal semaphore.h is included instead of the pthread version. Needless to say, the compiler isn't happy. Three options have been considered to fix this issue: - Use -iquote instead of -I. The -iquote option instructs gcc to only consider the header search path for headers included with the "" version. Meson unfortunately doesn't support this option. - Rename the internal semaphore.h header. This was deemed to be the beginning of a long whack-a-mole game, where namespace clashes with system libraries would appear over time (possibly dependent on particular system configurations) and would need to be constantly fixed. - Move the internal headers to another directory to create a unique namespace through path components. This causes lots of churn in all the existing source files through the all project. The first option would be best, but isn't available to us due to missing support in meson. Even if -iquote support was added, we would need to fix the problem before a new version of meson containing the required support would be released. The third option is thus the only practical solution available. Bite the bullet, and do it, moving headers to include/libcamera/internal/. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Acked-by: Jacopo Mondi <jacopo@jmondi.org>
2020-03-18libcamera: PixelFormat: Mark all function arguments of type PixelFormat as ↵Niklas Söderlund
const reference PixelFormat was previously an alias for unsigned int but is now a class. Make all functions taking PixelFormat do so as a const reference. Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-03-18libcamera: PixelFormat: Make constructor explicitLaurent Pinchart
To achieve the goal of preventing unwanted conversion between a DRM and a V4L2 FourCC, make the PixelFormat constructor that takes an integer value explicit. All users of pixel formats flagged by the compiler are fixed. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
2020-03-18libcamera: PixelFormat: Turn into a classNiklas Söderlund
Create a class to represent a pixel format. This is done to add support for modifiers for the formats. So far no modifiers are added by any pipeline handler, all plumbing to deal with them is however in place. Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-03-18libcamera: pixelformats: include linux/drm_fourcc.hNiklas Söderlund
Instead of having to include linux/drm_fourcc.h everywhere a DRM FourCC is used in conjunction with PixelFormat include the header directly in pixelformats.h. Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-03-08v4l2: v4l2_camera_proxy: Fix sign compare compilation errorLaurent Pinchart
When compiling for ARM and uClibc, gcc-8.3.0 complains about comparison of integer expressions of different signedness: ../../src/v4l2/v4l2_camera_proxy.cpp: In member function ‘void* V4L2CameraProxy::mmap(void*, size_t, int, int, off_t)’: ../../src/v4l2/v4l2_camera_proxy.cpp:88:25: error: comparison of integer expressions of different signedness: ‘unsigned int’ and ‘off_t’ {aka ‘long int’} [-Werror=sign-compare] if (index * sizeimage_ != offset || length != sizeimage_) { ~~~~~~~~~~~~~~~~~~~^~~~~~~~~ Fix the compilation error with a cast. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
2020-02-13v4l2: Remove internal threadLaurent Pinchart
Now that libcamera creates threads internally and doesn't rely on an application-provided event loop, remove the thread from the V4L2 compatibility layer. The split between the V4L2CameraProxy and V4L2Camera classes is still kept to separate the V4L2 adaptation from camera operation. This may be further refactored later. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
2020-01-20v4l2: Extend device caps with V4L2_CAP_STREAMINGNicolas Dufresne
This capability tells the application that mmap() is supported. GStreamer would return an error saying there there is no input/output method supported by this device otherwise. This was tested with: LD_PRELOAD=$(pwd)/build/src/v4l2/v4l2-compat.so GST_DEBUG="v4l2*:7" gst-launch-1.0 v4l2src ! videoconvert ! autovideosink With this patch, GStreamer will reach playing state. It then blocks waiting on poll() which is not implemented yet on our side. Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
2020-01-14libcamera: Switch from utils::make_unique to std::make_uniqueLaurent Pinchart
Now that we're using C++-14, drop utils::make_unique for std::make_unique. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
2020-01-12libcamera: Switch to FrameBuffer interfaceNiklas Söderlund
Switch to the FrameBuffer interface where all buffers are treated as external buffers and are allocated outside the camera. Applications allocating buffers using libcamera are switched to use the FrameBufferAllocator helper. Follow-up changes to this one will finalize the transition to the new FrameBuffer interface by removing code that is left unused after this change. Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-01-12libcamera: buffer: Move captured metadata to FrameMetadataNiklas Söderlund
Move the metadata retrieved when dequeuing a V4L2 buffer into a FrameMetadata object. This is done as a step to migrate to the FrameBuffer interface as the functions added to Buffer around FrameMetadata match the ones in FrameBuffer. Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-01-12v4l2: camera_proxy: Call V4L2Camera::getBufferFd() directlyLaurent Pinchart
The V4L2Camera::getBufferFd() method doesn't need to run in the camera thread. Call it directly. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
2020-01-12v4l2: camera: Handle memory mapping of buffers directlyNiklas Söderlund
In the upcoming FrameBuffer API the memory mapping of buffers will be left to the user of the FrameBuffer objects. Prepare the V4L2 compatibility layer to this upcoming change to ease conversion to the new API. Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-01-12v4l2: Rename FrameMetadata to V4L2FrameMetadataNiklas Söderlund
With the upcoming FrameBuffer API a new library wide FrameMetadata object will be added which will replace the specific implementation in the V4L2 compatibility layer. Avoid name collisions while the new FrameBuffer API is added by renaming the V4L2 compatibility layer specific implementation until it can be replaced with the library wide implementation. Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-01-09v4l2: camera_proxy: Fix compilation error use of undeclared identifier 'ret'Niklas Söderlund
Refactoring of the camera_proxy have left the 'ret' variable undeclared, declare it. ../../src/v4l2/v4l2_camera_proxy.cpp:273:2: error: use of undeclared identifier 'ret' ret = vcam_->invokeMethod(&V4L2Camera::configure, ^ ../../src/v4l2/v4l2_camera_proxy.cpp:278:6: error: use of undeclared identifier 'ret' if (ret < 0) Fixes: fce110c6d961c3bb ("v4l2: camera_proxy: Break out try_fmt") Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Acked-by: Jacopo Mondi <jacopo@jmondi.org> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
2020-01-08v4l2: camera_proxy: Align trace message styleJacopo Mondi
Most of the ioctl handlers in the V4L2CameraProxy class have an empty line between the tracing printouts and the immediately following buffer type validation. Align the two occasions where such an empty line is missing with the others. Cosmetic change only. Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
2020-01-08v4l2: camera_proxy: Break out try_fmtJacopo Mondi
Calling vidioc_s_fmt() calls vidioc_try_fmt() duplicating prinouts. Breakout try format procedure and call it from both functions. Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
2020-01-08v4l2: camera_proxy: Fix try_fmt format conversionJacopo Mondi
The set pixelformat field of struct v4l2_pix_format structure was wrongly converted to PixelFormat by calling v4l2ToDrm(), with an already converted 'format' argument. Fix this by calling the right drmToV4l2() conversion function. Fixes: 0ce8f2390b52 ("v4l2: v4l2_compat: Add V4L2 compatibility layer") Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
2020-01-08v4l2: camera_proxy: Include <array>Laurent Pinchart
Commit 29c5508075c1 ("v4l2: camera_proxy: Create format info array") introduced usage of the std::array template class, but didn't include the corresponding header. This may cause a compilation breakage in the future if the indirect include of <array> disappears due to unrelated changes. Fix it. Fixed: 29c5508075c1 ("v4l2: camera_proxy: Create format info array") Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
2020-01-07v4l2: camera_proxy: Create format info arrayLaurent Pinchart
Create a PixelFormatInfo structure to store information about a format, and add a global array of format info for all the formats currently supported. Move the format helpers to use the information from the array. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
2020-01-07v4l2: camera_proxy: Rationalize arguments to format helpersLaurent Pinchart
To clarify code, adopt the following rules for format helpers: - All variables representing V4L2 pixel formats shall use uint32_t - All variables representing DRM pixel formats shall use PixelFormat - Functions returning positive values only shall not have a signed return type Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
2020-01-07v4l2: Use Object::invokeMethod() return valueLaurent Pinchart
Now that Object::invokeMethod() supports returning a value, use it and drop the return value method argument. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
2020-01-03v4l2: v4l2_compat: Add V4L2 compatibility layerPaul Elder
Add libcamera V4L2 compatibility layer. This initial implementation supports the minimal set of V4L2 operations, which allows getting, setting, and enumerating formats, and streaming frames from a video device. Some data about the wrapped V4L2 video device are hardcoded. Add a build option named 'v4l2' and adjust the build system to selectively compile the V4L2 compatibility layer. For now we match the V4L2 device node to a libcamera camera based on a devnum that a pipeline handler may optionally map to a libcamera camera. Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Jacopo Mondi <jacopo@jmondi.org> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>