Re: [PATCH v2 6/9] drm/vkms: Add YUV support

Pekka Paalanen
2024-02-26T12:19:20Z

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On Fri, 23 Feb 2024 12:37:26 +0100
Louis Chauvet <louis.chauvet@bootlin.com> wrote:

> From: Arthur Grillo <arthurgrillo@riseup.net>
>
> Add support to the YUV formats bellow:
>
> - NV12
> - NV16
> - NV24
> - NV21
> - NV61
> - NV42
> - YUV420
> - YUV422
> - YUV444
> - YVU420
> - YVU422
> - YVU444
>
> The conversion matrices of each encoding and range were obtained by
> rounding the values of the original conversion matrices multiplied by
> 2^8. This is done to avoid the use of fixed point operations.
>
> Signed-off-by: Arthur Grillo <arthurgrillo@riseup.net>
> [Louis Chauvet: Adapted Arthur's work and implemented the read_line_t
> callbacks for yuv formats]
> Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
> ---
> drivers/gpu/drm/vkms/vkms_composer.c | 2 +-
> drivers/gpu/drm/vkms/vkms_drv.h | 6 +-
> drivers/gpu/drm/vkms/vkms_formats.c | 289 +++++++++++++++++++++++++++++++++--
> drivers/gpu/drm/vkms/vkms_formats.h | 4 +
> drivers/gpu/drm/vkms/vkms_plane.c | 14 +-
> 5 files changed, 295 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
> index e555bf9c1aee..54fc5161d565 100644
> --- a/drivers/gpu/drm/vkms/vkms_composer.c
> +++ b/drivers/gpu/drm/vkms/vkms_composer.c
> @@ -312,7 +312,7 @@ static void blend(struct vkms_writeback_job *wb,
> * buffer [1]
> */
> current_plane->pixel_read_line(
> - current_plane->frame_info,
> + current_plane,
> x_start,
> y_start,
> direction,
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> index ccc5be009f15..a4f6456cb971 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.h
> +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> @@ -75,6 +75,8 @@ enum pixel_read_direction {
> READ_RIGHT
> };
>
> +struct vkms_plane_state;
> +
> /**
> <<<<<<< HEAD
> * typedef pixel_read_line_t - These functions are used to read a pixel line in the source frame,
> @@ -87,8 +89,8 @@ enum pixel_read_direction {
> * @out_pixel: Pointer where to write the pixel value. Pixels will be written between x_start and
> * x_end.
> */
> -typedef void (*pixel_read_line_t)(struct vkms_frame_info *frame_info, int x_start, int y_start, enum
> - pixel_read_direction direction, int count, struct pixel_argb_u16 out_pixel[]);
> +typedef void (*pixel_read_line_t)(struct vkms_plane_state *frame_info, int x_start, int y_start,
> + enum pixel_read_direction direction, int count, struct pixel_argb_u16 out_pixel[]);

This is the second or third time in this one series changing this type.
Could you not do the change once, in its own patch if possible?

>
> /**
> * vkms_plane_state - Driver specific plane state
> diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c
> index 46daea6d3ee9..515c80866a58 100644
> --- a/drivers/gpu/drm/vkms/vkms_formats.c
> +++ b/drivers/gpu/drm/vkms/vkms_formats.c
> @@ -33,7 +33,8 @@ static size_t packed_pixels_offset(const struct vkms_frame_info *frame_info, int
> */
> return fb->offsets[plane_index] +
> (y / drm_format_info_block_width(format, plane_index)) * fb->pitches[plane_index] +
> - (x / drm_format_info_block_height(format, plane_index)) * format->char_per_block[plane_index];
> + (x / drm_format_info_block_height(format, plane_index)) *
> + format->char_per_block[plane_index];

Shouldn't this be in the patch that added this code in the first place?

> }
>
> /**
> @@ -84,6 +85,32 @@ static int get_step_1x1(struct drm_framebuffer *fb, enum pixel_read_direction di
> }
> }
>
> +/**
> + * get_subsampling() - Get the subsampling value on a specific direction

subsampling divisor

> + */
> +static int get_subsampling(const struct drm_format_info *format,
> + enum pixel_read_direction direction)
> +{
> + if (direction == READ_LEFT || direction == READ_RIGHT)
> + return format->hsub;
> + else if (direction == READ_DOWN || direction == READ_UP)
> + return format->vsub;
> + return 1;

In this and the below function, personally I'd prefer switch-case, with
a cannot-happen-scream after the switch, so the compiler can warn about
unhandled enum values.

> +}
> +
> +/**
> + * get_subsampling_offset() - Get the subsampling offset to use when incrementing the pixel counter
> + */
> +static int get_subsampling_offset(const struct drm_format_info *format,
> + enum pixel_read_direction direction, int x_start, int y_start)

'start' values as "increments" for a pixel counter? Is something
misnamed here?

Is it an increment or an offset?

> +{
> + if (direction == READ_RIGHT || direction == READ_LEFT)
> + return x_start;
> + else if (direction == READ_DOWN || direction == READ_UP)
> + return y_start;
> + return 0;
> +}
> +
>
> /*
> * The following functions take pixel data (a, r, g, b, pixel, ...), convert them to the format
> @@ -130,6 +157,87 @@ static void RGB565_to_argb_u16(struct pixel_argb_u16 *out_pixel, const u16 *pixe
> out_pixel->b = drm_fixp2int_round(drm_fixp_mul(fp_b, fp_rb_ratio));
> }
>
> +static void ycbcr2rgb(const s16 m[3][3], u8 y, u8 cb, u8 cr, u8 y_offset, u8 *r, u8 *g, u8 *b)
> +{
> + s32 y_16, cb_16, cr_16;
> + s32 r_16, g_16, b_16;
> +
> + y_16 = y - y_offset;
> + cb_16 = cb - 128;
> + cr_16 = cr - 128;
> +
> + r_16 = m[0][0] * y_16 + m[0][1] * cb_16 + m[0][2] * cr_16;
> + g_16 = m[1][0] * y_16 + m[1][1] * cb_16 + m[1][2] * cr_16;
> + b_16 = m[2][0] * y_16 + m[2][1] * cb_16 + m[2][2] * cr_16;
> +
> + *r = clamp(r_16, 0, 0xffff) >> 8;
> + *g = clamp(g_16, 0, 0xffff) >> 8;
> + *b = clamp(b_16, 0, 0xffff) >> 8;
> +}
> +
> +static void yuv_u8_to_argb_u16(struct pixel_argb_u16 *argb_u16, const struct pixel_yuv_u8 *yuv_u8,
> + enum drm_color_encoding encoding, enum drm_color_range range)
> +{
> + static const s16 bt601_full[3][3] = {
> + { 256, 0, 359 },
> + { 256, -88, -183 },
> + { 256, 454, 0 },
> + };
> + static const s16 bt601[3][3] = {
> + { 298, 0, 409 },
> + { 298, -100, -208 },
> + { 298, 516, 0 },
> + };
> + static const s16 rec709_full[3][3] = {
> + { 256, 0, 408 },
> + { 256, -48, -120 },
> + { 256, 476, 0 },
> + };
> + static const s16 rec709[3][3] = {
> + { 298, 0, 459 },
> + { 298, -55, -136 },
> + { 298, 541, 0 },
> + };
> + static const s16 bt2020_full[3][3] = {
> + { 256, 0, 377 },
> + { 256, -42, -146 },
> + { 256, 482, 0 },
> + };
> + static const s16 bt2020[3][3] = {
> + { 298, 0, 430 },
> + { 298, -48, -167 },
> + { 298, 548, 0 },
> + };
> +
> + u8 r = 0;
> + u8 g = 0;
> + u8 b = 0;
> + bool full = range == DRM_COLOR_YCBCR_FULL_RANGE;
> + unsigned int y_offset = full ? 0 : 16;
> +
> + switch (encoding) {
> + case DRM_COLOR_YCBCR_BT601:
> + ycbcr2rgb(full ? bt601_full : bt601,

Doing all these conditional again pixel by pixel is probably
inefficient. Just like with the line reading functions, you could pick
the matrix in advance.

> + yuv_u8->y, yuv_u8->u, yuv_u8->v, y_offset, &r, &g, &b);
> + break;
> + case DRM_COLOR_YCBCR_BT709:
> + ycbcr2rgb(full ? rec709_full : rec709,
> + yuv_u8->y, yuv_u8->u, yuv_u8->v, y_offset, &r, &g, &b);
> + break;
> + case DRM_COLOR_YCBCR_BT2020:
> + ycbcr2rgb(full ? bt2020_full : bt2020,
> + yuv_u8->y, yuv_u8->u, yuv_u8->v, y_offset, &r, &g, &b);
> + break;
> + default:
> + pr_warn_once("Not supported color encoding\n");
> + break;
> + }
> +
> + argb_u16->r = r * 257;
> + argb_u16->g = g * 257;
> + argb_u16->b = b * 257;

I wonder. Using 8-bit fixed point precision seems quite coarse for
8-bit pixel formats, and it's going to be insufficient for higher bit
depths. Was supporting e.g. 10-bit YUV considered? There is even
deeper, too, like DRM_FORMAT_P016.

> +}
> +
> /*
> * The following functions are read_line function for each pixel format supported by VKMS.
> *
> @@ -142,13 +250,13 @@ static void RGB565_to_argb_u16(struct pixel_argb_u16 *out_pixel, const u16 *pixe
> * [1]: https://lore.kernel.org/dri-devel/d258c8dc-78e9-4509-9037-a98f7f33b3a3@riseup.net/
> */
>
> -static void ARGB8888_read_line(struct vkms_frame_info *frame_info, int x_start, int y_start,
> +static void ARGB8888_read_line(struct vkms_plane_state *plane, int x_start, int y_start,
> enum pixel_read_direction direction, int count,
> struct pixel_argb_u16 out_pixel[])
> {
> - u8 *src_pixels = packed_pixels_addr(frame_info, x_start, y_start, 0);
> + u8 *src_pixels = packed_pixels_addr(plane->frame_info, x_start, y_start, 0);
>
> - int step = get_step_1x1(frame_info->fb, direction, 0);
> + int step = get_step_1x1(plane->frame_info->fb, direction, 0);

These are the kind of changes I would not expect to see in a patch
adding YUV support. There are a lot of them, too.

>
> while (count) {
> u8 *px = (u8 *)src_pixels;
> @@ -160,13 +268,13 @@ static void ARGB8888_read_line(struct vkms_frame_info *frame_info, int x_start,
> }
> }
>
> -static void XRGB8888_read_line(struct vkms_frame_info *frame_info, int x_start, int y_start,
> +static void XRGB8888_read_line(struct vkms_plane_state *plane, int x_start, int y_start,
> enum pixel_read_direction direction, int count,
> struct pixel_argb_u16 out_pixel[])
> {
> - u8 *src_pixels = packed_pixels_addr(frame_info, x_start, y_start, 0);
> + u8 *src_pixels = packed_pixels_addr(plane->frame_info, x_start, y_start, 0);
>
> - int step = get_step_1x1(frame_info->fb, direction, 0);
> + int step = get_step_1x1(plane->frame_info->fb, direction, 0);
>
> while (count) {
> u8 *px = (u8 *)src_pixels;
> @@ -178,13 +286,13 @@ static void XRGB8888_read_line(struct vkms_frame_info *frame_info, int x_start,
> }
> }
>
> -static void ARGB16161616_read_line(struct vkms_frame_info *frame_info, int x_start, int y_start,
> +static void ARGB16161616_read_line(struct vkms_plane_state *plane, int x_start, int y_start,
> enum pixel_read_direction direction, int count,
> struct pixel_argb_u16 out_pixel[])
> {
> - u8 *src_pixels = packed_pixels_addr(frame_info, x_start, y_start, 0);
> + u8 *src_pixels = packed_pixels_addr(plane->frame_info, x_start, y_start, 0);
>
> - int step = get_step_1x1(frame_info->fb, direction, 0);
> + int step = get_step_1x1(plane->frame_info->fb, direction, 0);
>
> while (count) {
> u16 *px = (u16 *)src_pixels;
> @@ -196,13 +304,13 @@ static void ARGB16161616_read_line(struct vkms_frame_info *frame_info, int x_sta
> }
> }
>
> -static void XRGB16161616_read_line(struct vkms_frame_info *frame_info, int x_start, int y_start,
> +static void XRGB16161616_read_line(struct vkms_plane_state *plane, int x_start, int y_start,
> enum pixel_read_direction direction, int count,
> struct pixel_argb_u16 out_pixel[])
> {
> - u8 *src_pixels = packed_pixels_addr(frame_info, x_start, y_start, 0);
> + u8 *src_pixels = packed_pixels_addr(plane->frame_info, x_start, y_start, 0);
>
> - int step = get_step_1x1(frame_info->fb, direction, 0);
> + int step = get_step_1x1(plane->frame_info->fb, direction, 0);
>
> while (count) {
> u16 *px = (u16 *)src_pixels;
> @@ -214,13 +322,13 @@ static void XRGB16161616_read_line(struct vkms_frame_info *frame_info, int x_sta
> }
> }
>
> -static void RGB565_read_line(struct vkms_frame_info *frame_info, int x_start, int y_start,
> +static void RGB565_read_line(struct vkms_plane_state *plane, int x_start, int y_start,
> enum pixel_read_direction direction, int count,
> struct pixel_argb_u16 out_pixel[])
> {
> - u8 *src_pixels = packed_pixels_addr(frame_info, x_start, y_start, 0);
> + u8 *src_pixels = packed_pixels_addr(plane->frame_info, x_start, y_start, 0);
>
> - int step = get_step_1x1(frame_info->fb, direction, 0);
> + int step = get_step_1x1(plane->frame_info->fb, direction, 0);
>
> while (count) {
> u16 *px = (u16 *)src_pixels;
> @@ -232,6 +340,139 @@ static void RGB565_read_line(struct vkms_frame_info *frame_info, int x_start, in
> }
> }
>
> +static void semi_planar_yuv_read_line(struct vkms_plane_state *plane, int x_start, int y_start,
> + enum pixel_read_direction direction, int count,
> + struct pixel_argb_u16 out_pixel[])
> +{
> + u8 *y_plane = packed_pixels_addr(plane->frame_info, x_start, y_start, 0);
> + u8 *uv_plane = packed_pixels_addr(plane->frame_info,
> + x_start / plane->frame_info->fb->format->hsub,
> + y_start / plane->frame_info->fb->format->vsub,
> + 1);
> + struct pixel_yuv_u8 yuv_u8;
> + int step_y = get_step_1x1(plane->frame_info->fb, direction, 0);
> + int step_uv = get_step_1x1(plane->frame_info->fb, direction, 1);
> + int subsampling = get_subsampling(plane->frame_info->fb->format, direction);
> + int subsampling_offset = get_subsampling_offset(plane->frame_info->fb->format, direction,
> + x_start, y_start); // 0
> +
> + for (int i = 0; i < count; i++) {
> + yuv_u8.y = y_plane[0];
> + yuv_u8.u = uv_plane[0];
> + yuv_u8.v = uv_plane[1];
> +
> + yuv_u8_to_argb_u16(out_pixel, &yuv_u8, plane->base.base.color_encoding,
> + plane->base.base.color_range);

Oh, so this was the reason to change the read-line function signature.
Maybe just stash a pointer to the right matrix and the right y_offset
in frame_info instead?

> + out_pixel += 1;
> + y_plane += step_y;
> + if ((i + subsampling_offset + 1) % subsampling == 0)
> + uv_plane += step_uv;
> + }
> +}
> +
> +static void semi_planar_yvu_read_line(struct vkms_plane_state *plane, int x_start, int y_start,
> + enum pixel_read_direction direction, int count,
> + struct pixel_argb_u16 out_pixel[])
> +{
> + u8 *y_plane = packed_pixels_addr(plane->frame_info, x_start, y_start, 0);
> + u8 *vu_plane = packed_pixels_addr(plane->frame_info,
> + x_start / plane->frame_info->fb->format->hsub,
> + y_start / plane->frame_info->fb->format->vsub,
> + 1);
> + struct pixel_yuv_u8 yuv_u8;
> + int step_y = get_step_1x1(plane->frame_info->fb, direction, 0);
> + int step_vu = get_step_1x1(plane->frame_info->fb, direction, 1);
> + int subsampling = get_subsampling(plane->frame_info->fb->format, direction);
> + int subsampling_offset = get_subsampling_offset(plane->frame_info->fb->format, direction,
> + x_start, y_start);
> + for (int i = 0; i < count; i++) {
> + yuv_u8.y = y_plane[0];
> + yuv_u8.u = vu_plane[1];
> + yuv_u8.v = vu_plane[0];

You could swap matrix columns instead of writing this whole new
function for UV vs. VU. Just an idea.

Thanks,
pq

> +
> + yuv_u8_to_argb_u16(out_pixel, &yuv_u8, plane->base.base.color_encoding,
> + plane->base.base.color_range);
> + out_pixel += 1;
> + y_plane += step_y;
> + if ((i + subsampling_offset + 1) % subsampling == 0)
> + vu_plane += step_vu;
> + }
> +}
> +
> +static void planar_yuv_read_line(struct vkms_plane_state *plane, int x_start, int y_start,
> + enum pixel_read_direction direction, int count,
> + struct pixel_argb_u16 out_pixel[])
> +{
> + u8 *y_plane = packed_pixels_addr(plane->frame_info, x_start, y_start, 0);
> + u8 *u_plane = packed_pixels_addr(plane->frame_info,
> + x_start / plane->frame_info->fb->format->hsub,
> + y_start / plane->frame_info->fb->format->vsub,
> + 1);
> + u8 *v_plane = packed_pixels_addr(plane->frame_info,
> + x_start / plane->frame_info->fb->format->hsub,
> + y_start / plane->frame_info->fb->format->vsub,
> + 2);
> + struct pixel_yuv_u8 yuv_u8;
> + int step_y = get_step_1x1(plane->frame_info->fb, direction, 0);
> + int step_u = get_step_1x1(plane->frame_info->fb, direction, 1);
> + int step_v = get_step_1x1(plane->frame_info->fb, direction, 2);
> + int subsampling = get_subsampling(plane->frame_info->fb->format, direction);
> + int subsampling_offset = get_subsampling_offset(plane->frame_info->fb->format, direction,
> + x_start, y_start);
> +
> + for (int i = 0; i < count; i++) {
> + yuv_u8.y = *y_plane;
> + yuv_u8.u = *u_plane;
> + yuv_u8.v = *v_plane;
> +
> + yuv_u8_to_argb_u16(out_pixel, &yuv_u8, plane->base.base.color_encoding,
> + plane->base.base.color_range);
> + out_pixel += 1;
> + y_plane += step_y;
> + if ((i + subsampling_offset + 1) % subsampling == 0) {
> + u_plane += step_u;
> + v_plane += step_v;
> + }
> + }
> +}
> +
> +static void planar_yvu_read_line(struct vkms_plane_state *plane, int x_start, int y_start,
> + enum pixel_read_direction direction, int count,
> + struct pixel_argb_u16 out_pixel[])
> +{
> + u8 *y_plane = packed_pixels_addr(plane->frame_info, x_start, y_start, 0);
> + u8 *v_plane = packed_pixels_addr(plane->frame_info,
> + x_start / plane->frame_info->fb->format->hsub,
> + y_start / plane->frame_info->fb->format->vsub,
> + 1);
> + u8 *u_plane = packed_pixels_addr(plane->frame_info,
> + x_start / plane->frame_info->fb->format->hsub,
> + y_start / plane->frame_info->fb->format->vsub,
> + 2);
> + struct pixel_yuv_u8 yuv_u8;
> + int step_y = get_step_1x1(plane->frame_info->fb, direction, 0);
> + int step_u = get_step_1x1(plane->frame_info->fb, direction, 1);
> + int step_v = get_step_1x1(plane->frame_info->fb, direction, 2);
> + int subsampling = get_subsampling(plane->frame_info->fb->format, direction);
> + int subsampling_offset = get_subsampling_offset(plane->frame_info->fb->format, direction,
> + x_start, y_start);
> +
> + for (int i = 0; i < count; i++) {
> + yuv_u8.y = *y_plane;
> + yuv_u8.u = *u_plane;
> + yuv_u8.v = *v_plane;
> +
> + yuv_u8_to_argb_u16(out_pixel, &yuv_u8, plane->base.base.color_encoding,
> + plane->base.base.color_range);
> + out_pixel += 1;
> + y_plane += step_y;
> + if ((i + subsampling_offset + 1) % subsampling == 0) {
> + u_plane += step_u;
> + v_plane += step_v;
> + }
> + }
> +}
> +
> /*
> * The following functions take one argb_u16 pixel and convert it to a specific format. The
> * result is stored in @dst_pixels.
> @@ -344,6 +585,22 @@ pixel_read_line_t get_pixel_read_line_function(u32 format)
> return &XRGB16161616_read_line;
> case DRM_FORMAT_RGB565:
> return &RGB565_read_line;
> + case DRM_FORMAT_NV12:
> + case DRM_FORMAT_NV16:
> + case DRM_FORMAT_NV24:
> + return &semi_planar_yuv_read_line;
> + case DRM_FORMAT_NV21:
> + case DRM_FORMAT_NV61:
> + case DRM_FORMAT_NV42:
> + return &semi_planar_yvu_read_line;
> + case DRM_FORMAT_YUV420:
> + case DRM_FORMAT_YUV422:
> + case DRM_FORMAT_YUV444:
> + return &planar_yuv_read_line;
> + case DRM_FORMAT_YVU420:
> + case DRM_FORMAT_YVU422:
> + case DRM_FORMAT_YVU444:
> + return &planar_yvu_read_line;
> default:
> return (pixel_read_line_t)NULL;
> }
> diff --git a/drivers/gpu/drm/vkms/vkms_formats.h b/drivers/gpu/drm/vkms/vkms_formats.h
> index 8d2bef95ff79..5a3a9e1328d8 100644
> --- a/drivers/gpu/drm/vkms/vkms_formats.h
> +++ b/drivers/gpu/drm/vkms/vkms_formats.h
> @@ -9,4 +9,8 @@ pixel_read_line_t get_pixel_read_line_function(u32 format);
>
> pixel_write_t get_pixel_write_function(u32 format);
>
> +struct pixel_yuv_u8 {
> + u8 y, u, v;
> +};
> +
> #endif /* _VKMS_FORMATS_H_ */
> diff --git a/drivers/gpu/drm/vkms/vkms_plane.c b/drivers/gpu/drm/vkms/vkms_plane.c
> index 58c1c74742b5..427ca67c60ce 100644
> --- a/drivers/gpu/drm/vkms/vkms_plane.c
> +++ b/drivers/gpu/drm/vkms/vkms_plane.c
> @@ -17,7 +17,19 @@ static const u32 vkms_formats[] = {
> DRM_FORMAT_XRGB8888,
> DRM_FORMAT_XRGB16161616,
> DRM_FORMAT_ARGB16161616,
> - DRM_FORMAT_RGB565
> + DRM_FORMAT_RGB565,
> + DRM_FORMAT_NV12,
> + DRM_FORMAT_NV16,
> + DRM_FORMAT_NV24,
> + DRM_FORMAT_NV21,
> + DRM_FORMAT_NV61,
> + DRM_FORMAT_NV42,
> + DRM_FORMAT_YUV420,
> + DRM_FORMAT_YUV422,
> + DRM_FORMAT_YUV444,
> + DRM_FORMAT_YVU420,
> + DRM_FORMAT_YVU422,
> + DRM_FORMAT_YVU444
> };
>
> static struct drm_plane_state *
>

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