On 9/30/24 8:31 AM, Louis Chauvet wrote:
> From: Arthur Grillo <arthurgrillo@xxxxxxxxxx>
>
> Add support to the YUV formats bellow:
>
> - NV12/NV16/NV24
> - NV21/NV61/NV42
> - YUV420/YUV422/YUV444
> - YVU420/YVU422/YVU444
>
> The conversion from yuv to rgb is done with fixed-point arithmetic, using
> 32.32 fixed-point numbers and the drm_fixed helpers.
>
> To do the conversion, a specific matrix must be used for each color range
> (DRM_COLOR_*_RANGE) and encoding (DRM_COLOR_*). This matrix is stored in
> the `conversion_matrix` struct, along with the specific y_offset needed.
> This matrix is queried only once, in `vkms_plane_atomic_update` and
> stored in a `vkms_plane_state`. Those conversion matrices of each
> encoding and range were obtained by rounding the values of the original
> conversion matrices multiplied by 2^32. This is done to avoid the use of
> floating point operations.
>
> The same reading function is used for YUV and YVU formats. As the only
> difference between those two category of formats is the order of field, a
> simple swap in conversion matrix columns allows using the same function.
>
> Signed-off-by: Arthur Grillo <arthurgrillo@xxxxxxxxxx>
> [Louis Chauvet:
> - Adapted Arthur's work
> - Implemented the read_line_t callbacks for yuv
> - add struct conversion_matrix
> - store the whole conversion_matrix in the plane state
> - remove struct pixel_yuv_u8
> - update the commit message
> - Merge the modifications from Arthur]
> Signed-off-by: Louis Chauvet <louis.chauvet@xxxxxxxxxxx>
> ---
> drivers/gpu/drm/vkms/vkms_drv.h | 18 ++
> drivers/gpu/drm/vkms/vkms_formats.c | 353 ++++++++++++++++++++++++++++++++++++
> drivers/gpu/drm/vkms/vkms_formats.h | 4 +
> drivers/gpu/drm/vkms/vkms_plane.c | 16 +-
> 4 files changed, 390 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c
> index 0f6678420a11..adb1228e5201 100644
> --- a/drivers/gpu/drm/vkms/vkms_formats.c
> +++ b/drivers/gpu/drm/vkms/vkms_formats.c
> @@ -140,6 +140,51 @@ static void packed_pixels_addr_1x1(const struct vkms_frame_info *frame_info,
> *addr = (u8 *)frame_info->map[0].vaddr + offset;
> }
>
> +/**
> + * get_subsampling() - Get the subsampling divisor value on a specific direction
> + *
> + * @format: format to extarct the subsampling from
extract
> + * @direction: direction of the subsampling requested
> + */
> +static int get_subsampling(const struct drm_format_info *format,
> + enum pixel_read_direction direction)
> +{
> + switch (direction) {
> + case READ_BOTTOM_TO_TOP:
> + case READ_TOP_TO_BOTTOM:
> + return format->vsub;
> + case READ_RIGHT_TO_LEFT:
> + case READ_LEFT_TO_RIGHT:
> + return format->hsub;
> + }
> + WARN_ONCE(true, "Invalid direction for pixel reading: %d\n", direction);
> + return 1;
> +}
> +
> +/**
> + * get_subsampling_offset() - An offset for keeping the chroma siting consistent regardless of
> + * x_start and y_start values
> + *
> + * @direction: direction of the reading to properly compute this offset
> + * @x_start: x coordinate of the starting point of the readed line
read
> + * @y_start: y coordinate of the starting point of the readed line
read
> + */
> +static int get_subsampling_offset(enum pixel_read_direction direction, int x_start, int y_start)
> +{
