[libcamera-devel] [PATCH] libcamera: v4l2_subdevice: use G_FORMAT if ENUM_FRAME_SIZE isn't implemented

[Andrey Konovalov]

Many camera sensor drivers support only one frame size, and don't
implement VIDIOC_SUBDEV_ENUM_FRAME_SIZE ioctl. And libcamera fails
to enumerate such cameras as it doesn't get the list of resolutions
the sensor driver supports. Fix this by using VIDIOC_SUBDEV_G_FORMAT
to get the size of the sensor's active format when the ENUM_FRAME_SIZE
ioctl isn't implemented by the sensor driver.

Signed-off-by: Andrey Konovalov <andrey.konovalov at linaro.org>
---
 src/libcamera/v4l2_subdevice.cpp | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/libcamera/v4l2_subdevice.cpp b/src/libcamera/v4l2_subdevice.cpp
index f2bcd7f..fac7586 100644
--- a/src/libcamera/v4l2_subdevice.cpp
+++ b/src/libcamera/v4l2_subdevice.cpp
@@ -317,7 +317,25 @@ std::vector<SizeRange> V4L2Subdevice::enumPadSizes(unsigned int pad,
 				   sizeEnum.max_width, sizeEnum.max_height);
 	}
 
-	if (ret < 0 && ret != -EINVAL && ret != -ENOTTY) {
+	if (ret == -ENOTTY) {
+		struct v4l2_subdev_format format = {};
+
+		LOG(V4L2, Debug)
+			<< "VIDIOC_SUBDEV_ENUM_FRAME_SIZE not implemented "
+			<< "- trying VIDIOC_SUBDEV_G_FMT";
+		format.pad = pad;
+		format.which = V4L2_SUBDEV_FORMAT_ACTIVE;
+
+		ret = ioctl(VIDIOC_SUBDEV_G_FMT, &format);
+		if (ret == 0) {
+			sizes.emplace_back(format.format.width,
+					   format.format.height,
+					   format.format.width,
+					   format.format.height);
+		}
+	}
+
+	if (ret < 0 && ret != -EINVAL) {
 		LOG(V4L2, Error)
 			<< "Unable to enumerate sizes on pad " << pad
 			<< ": " << strerror(-ret);
-- 
2.17.1