On Mon Mar 9 16:07:40 2026 +0100, Maxime Ripard wrote: > The subdev format documentation has a subsection describing how to use > the media bus pixel codes for serial buses. While it describes the > sampling part well, it doesn't really describe the current convention > used for the components order. > > Let's improve that. > > Reviewed-by: Laurent Pinchart <[email protected]> > Signed-off-by: Maxime Ripard <[email protected]> > Signed-off-by: Sakari Ailus <[email protected]> > Signed-off-by: Hans Verkuil <[email protected]>
Patch committed. Thanks, Hans Verkuil .../userspace-api/media/v4l/subdev-formats.rst | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) --- diff --git a/Documentation/userspace-api/media/v4l/subdev-formats.rst b/Documentation/userspace-api/media/v4l/subdev-formats.rst index 896177c5334f..c9999b929773 100644 --- a/Documentation/userspace-api/media/v4l/subdev-formats.rst +++ b/Documentation/userspace-api/media/v4l/subdev-formats.rst @@ -159,14 +159,18 @@ formats in memory (a raw Bayer image won't be magically converted to JPEG just by storing it to memory), there is no one-to-one correspondence between them. -The media bus pixel codes document parallel formats. Should the pixel data be -transported over a serial bus, the media bus pixel code that describes a -parallel format that transfers a sample on a single clock cycle is used. For -instance, both MEDIA_BUS_FMT_BGR888_1X24 and MEDIA_BUS_FMT_BGR888_3X8 are used -on parallel busses for transferring an 8 bits per sample BGR data, whereas on -serial busses the data in this format is only referred to using -MEDIA_BUS_FMT_BGR888_1X24. This is because there is effectively only a single -way to transport that format on the serial busses. +While the media bus pixel codes are named based on how pixels are +transmitted on parallel buses, serial buses do not define separate +codes. By convention, they use the codes that transfer a sample on a +single clock cycle, and whose bit orders from LSB to MSB correspond to +the order in which colour components are transmitted on the serial bus. +For instance, the MIPI CSI-2 24-bit RGB (RGB888) format uses the +MEDIA_BUS_FMT_RGB888_1X24 media bus code because CSI-2 transmits the +blue colour component first, followed by green and red, and +MEDIA_BUS_FMT_RGB888_1X24 defines the first bit of blue at bit 0. +While used for 24-bit RGB data on parallel buses, the +MEDIA_BUS_FMT_RGB888_3X8 or MEDIA_BUS_FMT_BGR888_1X24 codes must not be +used for CSI-2. Packed RGB Formats ^^^^^^^^^^^^^^^^^^ _______________________________________________ linuxtv-commits mailing list -- [email protected] To unsubscribe send an email to [email protected]
