On Wed, 13 Mar 2024 18:45:01 +0100
Louis Chauvet <louis.chauvet@xxxxxxxxxxx> wrote:
> Introduce the usage of block_h/block_w to compute the offset and the
> pointer of a pixel. The previous implementation was specialized for
> planes with block_h == block_w == 1. To avoid confusion and allow easier
> implementation of tiled formats. It also remove the usage of the
> deprecated format field `cpp`.
>
> Introduce the plane_index parameter to get an offset/pointer on a
> different plane.
>
> Signed-off-by: Louis Chauvet <louis.chauvet@xxxxxxxxxxx>
> ---
> drivers/gpu/drm/vkms/vkms_formats.c | 76 +++++++++++++++++++++++++------------
> 1 file changed, 52 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c
> index b2f8dfc26c35..649d75d05b1f 100644
> --- a/drivers/gpu/drm/vkms/vkms_formats.c
> +++ b/drivers/gpu/drm/vkms/vkms_formats.c
> @@ -10,23 +10,43 @@
> #include "vkms_formats.h"
>
> /**
> - * pixel_offset() - Get the offset of the pixel at coordinates x/y in the first plane
> + * packed_pixels_offset() - Get the offset of the block containing the pixel at coordinates x/y
> *
> * @frame_info: Buffer metadata
> * @x: The x coordinate of the wanted pixel in the buffer
> * @y: The y coordinate of the wanted pixel in the buffer
> + * @plane_index: The index of the plane to use
> + * @offset: The returned offset inside the buffer of the block
> + * @rem_x,@rem_y: The returned coordinate of the requested pixel in the block
> *
> - * The caller must ensure that the framebuffer associated with this request uses a pixel format
> - * where block_h == block_w == 1.
> - * If this requirement is not fulfilled, the resulting offset can point to an other pixel or
> - * outside of the buffer.
> + * As some pixel formats store multiple pixels in a block (DRM_FORMAT_R* for example), some
> + * pixels are not individually addressable. This function return 3 values: the offset of the
> + * whole block, and the coordinate of the requested pixel inside this block.
> + * For example, if the format is DRM_FORMAT_R1 and the requested coordinate is 13,5, the offset
> + * will point to the byte 5*pitches + 13/8 (second byte of the 5th line), and the rem_x/rem_y
> + * coordinates will be (13 % 8, 5 % 1) = (5, 0)
> + *
> + * With this function, the caller just have to extract the correct pixel from the block.
> */
> -static size_t pixel_offset(const struct vkms_frame_info *frame_info, int x, int y)
> +static void packed_pixels_offset(const struct vkms_frame_info *frame_info, int x, int y,
> + int plane_index, int *offset, int *rem_x, int *rem_y)
> {
> struct drm_framebuffer *fb = frame_info->fb;
> + const struct drm_format_info *format = frame_info->fb->format;
> + /* Directly using x and y to multiply pitches and format->ccp is not sufficient because
> + * in some formats a block can represent multiple pixels.
> + *
> + * Dividing x and y by the block size allows to extract the correct offset of the block
> + * containing the pixel.
> + */
>
> - return fb->offsets[0] + (y * fb->pitches[0])
> - + (x * fb->format->cpp[0]);
> + int block_x = x / drm_format_info_block_width(format, plane_index);
> + int block_y = y / drm_format_info_block_height(format, plane_index);
> + *rem_x = x % drm_format_info_block_width(format, plane_index);
> + *rem_y = x % drm_format_info_block_height(format, plane_index);
typo: x should be y
> + *offset = fb->offsets[plane_index] +
> + block_y * fb->pitches[plane_index] +
> + block_x * format->char_per_block[plane_index];
> }
Ok, this function looks very much plausible for handling blocky
formats. Good.
>
> /**
> @@ -36,30 +56,35 @@ static size_t pixel_offset(const struct vkms_frame_info *frame_info, int x, int
> * @frame_info: Buffer metadata
> * @x: The x(width) coordinate inside the plane
> * @y: The y(height) coordinate inside the plane
> + * @plane_index: The index of the plane
> + * @addr: The returned pointer
> + * @rem_x,@rem_y: The returned coordinate of the requested pixel in the block
> *
> - * Takes the information stored in the frame_info, a pair of coordinates, and
> - * returns the address of the first color channel.
> - * This function assumes the channels are packed together, i.e. a color channel
> - * comes immediately after another in the memory. And therefore, this function
> - * doesn't work for YUV with chroma subsampling (e.g. YUV420 and NV21).
> + * Takes the information stored in the frame_info, a pair of coordinates, and returns the address
> + * of the block containing this pixel and the pixel position inside this block.
> *
> - * The caller must ensure that the framebuffer associated with this request uses a pixel format
> - * where block_h == block_w == 1, otherwise the returned pointer can be outside the buffer.
> + * See @packed_pixel_offset for details about rem_x/rem_y behavior.
> */
> -static void *packed_pixels_addr(const struct vkms_frame_info *frame_info,
> - int x, int y)
> +static void packed_pixels_addr(const struct vkms_frame_info *frame_info,
> + int x, int y, int plane_index, u8 **addr, int *rem_x,
> + int *rem_y)
> {
> - size_t offset = pixel_offset(frame_info, x, y);
> + int offset;
>
> - return (u8 *)frame_info->map[0].vaddr + offset;
> + packed_pixels_offset(frame_info, x, y, plane_index, &offset, rem_x, rem_y);
> + *addr = (u8 *)frame_info->map[0].vaddr + offset;
> }
>
> -static void *get_packed_src_addr(const struct vkms_frame_info *frame_info, int y)
> +static void *get_packed_src_addr(const struct vkms_frame_info *frame_info, int y,
> + int plane_index)
> {
> int x_src = frame_info->src.x1 >> 16;
> int y_src = y - frame_info->rotated.y1 + (frame_info->src.y1 >> 16);
> + u8 *addr;
> + int rem_x, rem_y;
>
> - return packed_pixels_addr(frame_info, x_src, y_src);
> + packed_pixels_addr(frame_info, x_src, y_src, plane_index, &addr, &rem_x, &rem_y);
How can the caller be not interested in rem_x, rem_y?
Maybe there is no IGT test that uses DRM_FORMAT_R1 FB on a plane and
has a source rectangle whose x is not divisible by 8 pixels?
Or maybe the FB is filled with a solid color instead of a pattern that
would show source rectangle positioning problems?
Maybe at this point of the series, this should assert that rem_x and
rem_y are zero? That's what vkms_compose_row() assumes, right?
Thanks,
pq
> + return addr;
> }
>
> static int get_x_position(const struct vkms_frame_info *frame_info, int limit, int x)
> @@ -168,14 +193,14 @@ void vkms_compose_row(struct line_buffer *stage_buffer, struct vkms_plane_state
> {
> struct pixel_argb_u16 *out_pixels = stage_buffer->pixels;
> struct vkms_frame_info *frame_info = plane->frame_info;
> - u8 *src_pixels = get_packed_src_addr(frame_info, y);
> + u8 *src_pixels = get_packed_src_addr(frame_info, y, 0);
> int limit = min_t(size_t, drm_rect_width(&frame_info->dst), stage_buffer->n_pixels);
>
> for (size_t x = 0; x < limit; x++, src_pixels += frame_info->fb->format->cpp[0]) {
> int x_pos = get_x_position(frame_info, limit, x);
>
> if (drm_rotation_90_or_270(frame_info->rotation))
> - src_pixels = get_packed_src_addr(frame_info, x + frame_info->rotated.y1)
> + src_pixels = get_packed_src_addr(frame_info, x + frame_info->rotated.y1, 0)
> + frame_info->fb->format->cpp[0] * y;
>
> plane->pixel_read(src_pixels, &out_pixels[x_pos]);
> @@ -276,7 +301,10 @@ void vkms_writeback_row(struct vkms_writeback_job *wb,
> {
> struct vkms_frame_info *frame_info = &wb->wb_frame_info;
> int x_dst = frame_info->dst.x1;
> - u8 *dst_pixels = packed_pixels_addr(frame_info, x_dst, y);
> + u8 *dst_pixels;
> + int rem_x, rem_y;
> +
> + packed_pixels_addr(frame_info, x_dst, y, 0, &dst_pixels, &rem_x, &rem_y);
> struct pixel_argb_u16 *in_pixels = src_buffer->pixels;
> int x_limit = min_t(size_t, drm_rect_width(&frame_info->dst), src_buffer->n_pixels);
>
>
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