libcamera: v4l2_videodevice: Drop toV4L2PixelFormat()

The V4L2VideoDevice::toV4L2PixelFormat() function is incorrectly
implemented, as it will pick a multi-planar format if the device
supports the multi-planar API, even if only single-planar formats are
supported. This currently works because the implementation calls
V4L2PixelFormat::fromPixelFormat(), which ignores the multiplanar
argument and always returns a single-planar format.

Fixing this isn't trivial. As we don't need to support multi-planar V4L2
formats at this point, drop the function instead of pretending
everything is fine, and call V4L2PixelFormat::fromPixelFormat() directly
from pipeline handlers. As the single-planar case is the most common,
set the multiplanar argument to false by default to avoid long lines.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>

1 files changed, 3 insertions, 4 deletions

diff --git a/Documentation/guides/pipeline-handler.rst b/Documentation/guides/pipeline-handler.rst
index 54c8e7f1..c0fb7147 100644
--- a/Documentation/guides/pipeline-handler.rst
+++ b/Documentation/guides/pipeline-handler.rst
@@ -970,8 +970,7 @@ with the fourcc and size attributes to apply directly to the capture device
 node. The fourcc attribute is a `V4L2PixelFormat`_ and differs from the
 ``libcamera::PixelFormat``. Converting the format requires knowledge of the
 plane configuration for multiplanar formats, so you must explicitly convert it
-using the helper ``V4L2VideoDevice::toV4L2PixelFormat()`` provided by the
-V4L2VideoDevice instance of which the format will be applied on.
+using the helper ``V4L2PixelFormat::fromPixelFormat()``.
 
 .. _V4L2DeviceFormat: http://libcamera.org/api-html/classlibcamera_1_1V4L2DeviceFormat.html
 .. _V4L2PixelFormat: http://libcamera.org/api-html/classlibcamera_1_1V4L2PixelFormat.html
@@ -981,7 +980,7 @@ Add the following code beneath the code from above:
 .. code-block:: cpp
 
    V4L2DeviceFormat format = {};
-   format.fourcc = data->video_->toV4L2PixelFormat(cfg.pixelFormat);
+   format.fourcc = V4L2PixelFormat::fromPixelFormat(cfg.pixelFormat);
    format.size = cfg.size;
 
 Set the video device format defined above using the
@@ -1001,7 +1000,7 @@ Continue the implementation with the following code:
           return ret;
 
    if (format.size != cfg.size ||
-          format.fourcc != data->video_->toV4L2PixelFormat(cfg.pixelFormat))
+          format.fourcc != V4L2PixelFormat::fromPixelFormat(cfg.pixelFormat))
           return -EINVAL;
 
 Finally, store and set stream-specific data reflecting the state of the stream.