On Tue, 09 Apr 2024 15:25:35 +0200
Louis Chauvet <[email protected]> wrote:

> This add the support for:
> - R1/R2/R4/R8
>
> R1 format was tested with [1] and [2].
>
> [1]: https://lore.kernel.org/r/[email protected]
> [2]: https://lore.kernel.org/igt-dev/[email protected]/
>
> Signed-off-by: Louis Chauvet <[email protected]>
> ---
> drivers/gpu/drm/vkms/vkms_formats.c | 101 ++++++++++++++++++++++++++++++++++++
> drivers/gpu/drm/vkms/vkms_plane.c | 4 ++
> 2 files changed, 105 insertions(+)
>
> diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c
> index ca9028c1ef1a..7f49995686fd 100644
> --- a/drivers/gpu/drm/vkms/vkms_formats.c
> +++ b/drivers/gpu/drm/vkms/vkms_formats.c
> @@ -237,6 +237,11 @@ static struct pixel_argb_u16 argb_u16_from_RGB565(const u16 *pixel)
> return out_pixel;
> }
>
> +static struct pixel_argb_u16 argb_u16_from_gray8(u8 gray)
> +{
> + return argb_u16_from_u8888(255, gray, gray, gray);
> +}
> +
> VISIBLE_IF_KUNIT struct pixel_argb_u16 argb_u16_from_yuv888(u8 y, u8 channel_1, u8 channel_2,
> const struct conversion_matrix *matrix)
> {
> @@ -302,6 +307,94 @@ static void magenta_to_argb_u16(const struct vkms_plane_state *plane, int x_star
> }
> }
>
> +static void Rx_read_line(const 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 bit_per_pixel, u8 lum_per_level)

Hi Louis,

I guess for R1, R2 and R4, you would get both bit_per_pixel and
lum_per_level from the pixel format info?

bits_per_pixel = drm_format_info_bpp(...)

lum_per_level = 0xFF / (1 << bits_per_pixel - 1) = 0xFF / mask

or even 0xFFFF so you get the 16-bit value directly.

> +{
> + struct pixel_argb_u16 *end = out_pixel + count;
> + u8 *src_pixels;
> + int rem_x, rem_y;
> +
> + WARN_ONCE(drm_format_info_block_height(plane->frame_info->fb->format, 0) != 1,
> + "%s() only support formats with block_h == 1", __func__);
> +
> + packed_pixels_addr(plane->frame_info, x_start, y_start, 0, &src_pixels, &rem_x, &rem_y);
> + int bit_offset = (8-bit_per_pixel) - rem_x * bit_per_pixel;
> + int step = get_block_step_byte(plane->frame_info->fb, direction, 0);
> + int mask = (0x1 << bit_per_pixel) - 1;

Bit masks are best unsigned, because a signed shift-right of a value
will replicate the old highest bit to all the new high bits. That might
be a surprise if the old value happens to be negative.

> +
> + if (direction == READ_LEFT_TO_RIGHT || direction == READ_RIGHT_TO_LEFT) {
> + int restart_bit_offset;
> + int step_bit_offset;
> +
> + if (direction == READ_LEFT_TO_RIGHT) {
> + restart_bit_offset = 8 - bit_per_pixel;
> + step_bit_offset = -bit_per_pixel;
> + } else {
> + restart_bit_offset = 0;
> + step_bit_offset = bit_per_pixel;
> + }
> +
> + while (out_pixel < end) {
> + u8 val = ((*src_pixels) >> bit_offset) & mask;
> +
> + *out_pixel = argb_u16_from_gray8(val * lum_per_level);
> +
> + bit_offset += step_bit_offset;
> + if (bit_offset < 0 || 8 <= bit_offset) {
> + bit_offset = restart_bit_offset;
> + src_pixels += step;
> + }
> + out_pixel += 1;
> + }
> + } else if (direction == READ_TOP_TO_BOTTOM || direction == READ_BOTTOM_TO_TOP) {
> + while (out_pixel < end) {
> + u8 val = (*src_pixels >> bit_offset) & mask;
> + *out_pixel = argb_u16_from_gray8(val * lum_per_level);
> + src_pixels += step;
> + out_pixel += 1;
> + }
> + }
> +}
> +
> +static void R1_read_line(const struct vkms_plane_state *plane, int x_start,
> + int y_start, enum pixel_read_direction direction, int count,
> + struct pixel_argb_u16 out_pixel[])
> +{
> + Rx_read_line(plane, x_start, y_start, direction, count, out_pixel, 1, 0xFF);
> +}
> +
> +static void R2_read_line(const struct vkms_plane_state *plane, int x_start,
> + int y_start, enum pixel_read_direction direction, int count,
> + struct pixel_argb_u16 out_pixel[])
> +{
> + Rx_read_line(plane, x_start, y_start, direction, count, out_pixel, 2, 0x55);
> +}
> +
> +static void R4_read_line(const struct vkms_plane_state *plane, int x_start,
> + int y_start, enum pixel_read_direction direction, int count,
> + struct pixel_argb_u16 out_pixel[])
> +{
> + Rx_read_line(plane, x_start, y_start, direction, count, out_pixel, 4, 0x11);
> +}
> +
> +static void R8_read_line(const struct vkms_plane_state *plane, int x_start,
> + int y_start, enum pixel_read_direction direction, int count,
> + struct pixel_argb_u16 out_pixel[])
> +{
> + struct pixel_argb_u16 *end = out_pixel + count;
> + u8 *src_pixels;
> + int step = get_block_step_byte(plane->frame_info->fb, direction, 0);
> +
> + packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
> +
> + while (out_pixel < end) {
> + *out_pixel = argb_u16_from_gray8(*src_pixels);
> + src_pixels += step;
> + out_pixel += 1;
> + }
> +}
> +
> static void ARGB8888_read_line(const struct vkms_plane_state *plane, int x_start, int y_start,
> enum pixel_read_direction direction, int count,
> struct pixel_argb_u16 out_pixel[])
> @@ -625,6 +718,14 @@ pixel_read_line_t get_pixel_read_line_function(u32 format)
> case DRM_FORMAT_YVU422:
> case DRM_FORMAT_YVU444:
> return &planar_yuv_read_line;
> + case DRM_FORMAT_R1:
> + return &R1_read_line;
> + case DRM_FORMAT_R2:
> + return &R2_read_line;
> + case DRM_FORMAT_R4:
> + return &R4_read_line;
> + case DRM_FORMAT_R8:
> + return &R8_read_line;
> default:
> /*
> * This is a bug in vkms_plane_atomic_check(). All the supported
> diff --git a/drivers/gpu/drm/vkms/vkms_plane.c b/drivers/gpu/drm/vkms/vkms_plane.c
> index 8f764a108b00..67f891e7ac58 100644
> --- a/drivers/gpu/drm/vkms/vkms_plane.c
> +++ b/drivers/gpu/drm/vkms/vkms_plane.c
> @@ -30,6 +30,10 @@ static const u32 vkms_formats[] = {
> DRM_FORMAT_YVU420,
> DRM_FORMAT_YVU422,
> DRM_FORMAT_YVU444,
> + DRM_FORMAT_R1,
> + DRM_FORMAT_R2,
> + DRM_FORMAT_R4,
> + DRM_FORMAT_R8,
> };
>
> static struct drm_plane_state *
>

This patch looks good to me, and the R8_read_line() is ok to have
separately, I guess for performance reasons.

I suggested a way to reduce the repetition between R1, R2, R4 a little
bit. With or without that:

Reviewed-by: Pekka Paalanen <[email protected]>

Thanks,
pq

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