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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Corruption with DMA ring on cayman"
href="https://bugs.freedesktop.org/show_bug.cgi?id=60802#c53">Comment # 53</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Corruption with DMA ring on cayman"
href="https://bugs.freedesktop.org/show_bug.cgi?id=60802">bug 60802</a>
from <span class="vcard"><a class="email" href="mailto:alexandre.f.demers@gmail.com" title="Alexandre Demers <alexandre.f.demers@gmail.com>"> <span class="fn">Alexandre Demers</span></a>
</span></b>
<pre>(In reply to <a href="show_bug.cgi?id=60802#c50">comment #50</a>)
<span class="quote">> I believe I have the source of the bug, it appears that there is a special
> case for Caymen GPUs that isn't handled in the DMA code path. In
> evergreen_state.c within the method evergreen_create_sampler_view_custom
> there is the chunk of code
>
> /* 128 bit formats require tile type = 1 */
> if (rscreen->chip_class == CAYMAN) {
> if (util_format_get_blocksize(pipe_format) >= 16)
> non_disp_tiling = 1;
> }
>
> however, within evergreen_dma_copy_tile in the same source file no such code
> exists. I tested whether this was the case or not by placing the lines of
> code
>
> if (util_format_get_blocksize(dst->format) >= 16) {
> printf("Caymen non disp tiling skipping dma tile\n");
> return FALSE;
> }
>
> before the call to evergreen_dma_copy_tile in evergreen_dma_blit, and the
> corruption no longer appeared. (having this checks skips the DMA path for
> this case and goes through the normal path, which would be
> evergreen_create_sampler_view_custom I believe)
>
> I'm not sure which bits in the DMA packet control this setting.</span >
Your observations are right, using your trick does indeed remove the
corruptions.</pre>
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