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.chau...@bootlin.com>
---
 drivers/gpu/drm/vkms/vkms_formats.c | 59 +++++++++++++++++++++----------------
 1 file changed, 34 insertions(+), 25 deletions(-)

diff --git a/drivers/gpu/drm/vkms/vkms_formats.c 
b/drivers/gpu/drm/vkms/vkms_formats.c
index bdd15964ce24..089e4bdd5da8 100644
--- a/drivers/gpu/drm/vkms/vkms_formats.c
+++ b/drivers/gpu/drm/vkms/vkms_formats.c
@@ -10,23 +10,33 @@
 #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
  *
- * 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.
+ * The returned offset correspond to the offset of the block containing the 
pixel at coordinates
+ * x/y.
+ * The caller must use this offset with care, as for formats with block_h != 1 
or block_w != 1
+ * the requested pixel value may have to be extracted from the block, even if 
they are
+ * individually addressable.
  */
-static size_t pixel_offset(const struct vkms_frame_info *frame_info, int x, 
int y)
+static size_t packed_pixels_offset(const struct vkms_frame_info *frame_info, 
int x, int y,
+                                  size_t plane_index)
 {
        struct drm_framebuffer *fb = frame_info->fb;
-
-       return fb->offsets[0] + (y * fb->pitches[0])
-                             + (x * fb->format->cpp[0]);
+       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[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];
 }
 
 /**
@@ -36,30 +46,29 @@ 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
  *
- * 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.
  *
- * 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.
+ * The returned pointer points to the block containing the pixel at 
coordinates x/y.
+ * The caller must use this pointer with care, as for formats with block_h != 
1 or block_w != 1
+ * the requested pixel may have to be extracted from the block, even if they 
are
+ * individually addressable.
  */
 static void *packed_pixels_addr(const struct vkms_frame_info *frame_info,
-                               int x, int y)
+                               int x, int y, size_t plane_index)
 {
-       size_t offset = pixel_offset(frame_info, x, y);
-
-       return (u8 *)frame_info->map[0].vaddr + offset;
+       return (u8 *)frame_info->map[0].vaddr + 
packed_pixels_offset(frame_info, x, y, plane_index);
 }
 
-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,
+                                size_t plane_index)
 {
        int x_src = frame_info->src.x1 >> 16;
        int y_src = y - frame_info->rotated.y1 + (frame_info->src.y1 >> 16);
 
-       return packed_pixels_addr(frame_info, x_src, y_src);
+       return packed_pixels_addr(frame_info, x_src, y_src, plane_index);
 }
 
 static int get_x_position(const struct vkms_frame_info *frame_info, int limit, 
int x)
@@ -168,14 +177,14 @@ 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]);
@@ -275,7 +284,7 @@ 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 = packed_pixels_addr(frame_info, x_dst, y, 0);
        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);
 

-- 
2.43.0

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