The i.MX DCSS driver is open coding drm_fb_dma_get_gem_clipped_addr(),
with only a slight difference of rounding down the X offset for the
first plane if the format is packed, sub-sampled YUV. This is likely
to correct the buffer address to the first pixel of the 2-pixel group.
Otherwise the hardware will start the scan-out from the second pixel,
which leads to the U/V components getting swapped around, and the
chroma component of the next pixel group being used.

Switch to drm_fb_dma_get_gem_clipped_addr(), and offset the address by
a pixel if the X offset is odd.

Signed-off-by: Chen-Yu Tsai <[email protected]>
---
 drivers/gpu/drm/imx/dcss/dcss-plane.c | 34 +++++++++++----------------
 1 file changed, 14 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/imx/dcss/dcss-plane.c 
b/drivers/gpu/drm/imx/dcss/dcss-plane.c
index 303e93fd036c..580d9cfb4053 100644
--- a/drivers/gpu/drm/imx/dcss/dcss-plane.c
+++ b/drivers/gpu/drm/imx/dcss/dcss-plane.c
@@ -219,28 +219,22 @@ static void dcss_plane_atomic_set_base(struct dcss_plane 
*dcss_plane)
        struct dcss_dev *dcss = plane->dev->dev_private;
        struct drm_framebuffer *fb = state->fb;
        const struct drm_format_info *format = fb->format;
-       struct drm_gem_dma_object *dma_obj = drm_fb_dma_get_gem_obj(fb, 0);
        unsigned long p1_ba = 0, p2_ba = 0;
 
-       if (!format->is_yuv ||
-           format->format == DRM_FORMAT_NV12 ||
-           format->format == DRM_FORMAT_NV21)
-               p1_ba = dma_obj->dma_addr + fb->offsets[0] +
-                       fb->pitches[0] * (state->src.y1 >> 16) +
-                       format->char_per_block[0] * (state->src.x1 >> 16);
-       else if (format->format == DRM_FORMAT_UYVY ||
-                format->format == DRM_FORMAT_VYUY ||
-                format->format == DRM_FORMAT_YUYV ||
-                format->format == DRM_FORMAT_YVYU)
-               p1_ba = dma_obj->dma_addr + fb->offsets[0] +
-                       fb->pitches[0] * (state->src.y1 >> 16) +
-                       2 * format->char_per_block[0] * (state->src.x1 >> 17);
-
-       if (format->format == DRM_FORMAT_NV12 ||
-           format->format == DRM_FORMAT_NV21)
-               p2_ba = dma_obj->dma_addr + fb->offsets[1] +
-                       (((fb->pitches[1] >> 1) * (state->src.y1 >> 17) +
-                       (state->src.x1 >> 17)) << 1);
+       p1_ba = drm_fb_dma_get_gem_clipped_addr(fb, state, 0);
+
+       /*
+        * TODO fix address until helpers know packed, sub-sampled YUV format 
block size
+        *
+        * The buffer address for packed, sub-sampled YUV formats such as 
DRM_FORMAT_UYVY
+        * need to be on the first pixel of each pixel group or block. 
Otherwise the first
+        * pixel of the next pixel group is read and the U/V values get swapped 
around.
+        */
+       if (drm_format_info_is_yuv_packed(format))
+               p1_ba -= ((state->src.x1 >> 16) & 1) * format->cpp[0];
+
+       if (format->num_planes > 1)
+               p2_ba = drm_fb_dma_get_gem_clipped_addr(fb, state, 1);
 
        dcss_dpr_addr_set(dcss->dpr, dcss_plane->ch_num, p1_ba, p2_ba,
                          fb->pitches[0]);
-- 
2.55.0.1032.g73a4cd73de-goog

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