[PATCH 4/4] drm/imx/dcss: plane: Switch to drm_fb_dma_get_gem_clipped_addr()

[Chen-Yu Tsai <wenst@chromium.org>]

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 <wenst@chromium.org>
---
 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]);
-- 
2.55.0.979.g7e5102b832-goog