[libcamera-devel] [PATCH v3 5/6] libcamera: v4l2_videodevice: Match formats supported by the device

[Jacopo Mondi]

Now that V4L2PixelFormat::fromPixelFormat() returns a list of formats
to chose from, select the one supported by the video device by matching
against the list of supported pixel formats.

The first format found to match one of the device supported ones is
returned.

As the list of pixel formats supported by the video device does not
change at run-time, cache it at device open() time.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 include/libcamera/internal/v4l2_videodevice.h |  1 +
 src/libcamera/v4l2_videodevice.cpp            | 28 +++++++++++++++----
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/include/libcamera/internal/v4l2_videodevice.h b/include/libcamera/internal/v4l2_videodevice.h
index 29fa0bbaf670..6fe81d5e4cf0 100644
--- a/include/libcamera/internal/v4l2_videodevice.h
+++ b/include/libcamera/internal/v4l2_videodevice.h
@@ -268,6 +268,7 @@ private:
 	V4L2Capability caps_;
 	V4L2DeviceFormat format_;
 	const PixelFormatInfo *formatInfo_;
+	std::vector<V4L2PixelFormat> pixelFormats_;
 
 	enum v4l2_buf_type bufferType_;
 	enum v4l2_memory memoryType_;
diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
index 2ca22f485d45..0aeaae6ad573 100644
--- a/src/libcamera/v4l2_videodevice.cpp
+++ b/src/libcamera/v4l2_videodevice.cpp
@@ -633,6 +633,8 @@ int V4L2VideoDevice::open()
 		<< "Opened device " << caps_.bus_info() << ": "
 		<< caps_.driver() << ": " << caps_.card();
 
+	pixelFormats_ = enumPixelformats(0);
+
 	ret = getFormat(&format_);
 	if (ret) {
 		LOG(V4L2, Error) << "Failed to get format";
@@ -726,6 +728,8 @@ int V4L2VideoDevice::open(SharedFD handle, enum v4l2_buf_type type)
 		<< "Opened device " << caps_.bus_info() << ": "
 		<< caps_.driver() << ": " << caps_.card();
 
+	pixelFormats_ = enumPixelformats(0);
+
 	ret = getFormat(&format_);
 	if (ret) {
 		LOG(V4L2, Error) << "Failed to get format";
@@ -1990,17 +1994,31 @@ V4L2VideoDevice::fromEntityName(const MediaDevice *media,
 }
 
 /**
- * \brief Convert \a PixelFormat to its corresponding V4L2 FourCC
+ * \brief Convert \a PixelFormat to one of the device supported V4L2 FourCC
  * \param[in] pixelFormat The PixelFormat to convert
  *
- * The V4L2 format variant the function returns the contiguous version
- * unconditionally.
+ * Convert a\ pixelformat to a V4L2 FourCC that is known to be supported by
+ * the video device.
  *
- * \return The V4L2_PIX_FMT_* pixel format code corresponding to \a pixelFormat
+ * \return The V4L2PixelFormat corresponding to \a pixelFormat or an invalid
+ * PixelFormat if \a pixelFormat is not supported by the video device
  */
 V4L2PixelFormat V4L2VideoDevice::toV4L2PixelFormat(const PixelFormat &pixelFormat) const
 {
-	return V4L2PixelFormat::fromPixelFormat(pixelFormat)[0];
+	std::vector<V4L2PixelFormat> v4l2PixelFormats =
+		V4L2PixelFormat::fromPixelFormat(pixelFormat);
+
+	for (const V4L2PixelFormat &v4l2Format : v4l2PixelFormats) {
+		auto it = std::find_if(pixelFormats_.begin(), pixelFormats_.end(),
+				       [&v4l2Format](const V4L2PixelFormat &devFormat) {
+					       return v4l2Format == devFormat;
+				       });
+
+		if (it != pixelFormats_.end())
+			return v4l2Format;
+	}
+
+	return {};
 }
 
 /**
-- 
2.37.1