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drm: Use horizontal and vertical chroma subsampling factor while calculating offsets in the physical address of framebuffer 

For multi-planar formats, while calculating offsets in planes with index greater than 0
(ie second plane, third plane, etc), one needs to divide (src_x * cpp) with horizontal
chroma subsampling factor and (src_y * pitch) with vertical chroma subsampling factor.

The reason being that the planes contain subsampled (ie reduced) data (by a factor of 2) and thus
while calculating the byte position coresponding to the x and y co-ordinates, one needs to
divide it with the sampling factor.

Signed-off-by: Ayan Kumar halder <ayan.halder@arm.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Link: https://patchwork.kernel.org/patch/10569263/
This commit is contained in:
Ayan Kumar Halder 2018-08-17 17:54:00 +01:00
parent 065e8c8ff0
commit c76abab59b
1 changed files with 9 additions and 2 deletions
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11
drivers/gpu/drm/drm_fb_cma_helper.c
View File

@ -86,14 +86,21 @@ dma_addr_t drm_fb_cma_get_gem_addr(struct drm_framebuffer *fb,
{
struct drm_gem_cma_object *obj;
dma_addr_t paddr;
u8 h_div = 1, v_div = 1;
obj = drm_fb_cma_get_gem_obj(fb, plane);
if (!obj)
return 0;
paddr = obj->paddr + fb->offsets[plane];
paddr += fb->format->cpp[plane] * (state->src_x >> 16);
paddr += fb->pitches[plane] * (state->src_y >> 16);
if (plane > 0) {
h_div = fb->format->hsub;
v_div = fb->format->vsub;
}
paddr += (fb->format->cpp[plane] * (state->src_x >> 16)) / h_div;
paddr += (fb->pitches[plane] * (state->src_y >> 16)) / v_div;
return paddr;
}