On Thu, Jun 14, 2018 at 04:18:30PM +0300, Martin Peres wrote: > This fixes screenshots using 8k+ wide display setups in modesetting. > > Chris Wilson even recommended the changes in intel_mipmap_tree.c > should read 131072 instead of 65535, but I for sure got confused by > his explanation. > > In any case, I would like to use this RFC patch as a forum to discuss > why the fallback path is broken[1], and as to what should be the > limits for HW-accelerated blits now that we got rid of the blitter > usage on recent platforms. >
Hi, My understanding is that the fallback path is broken because we silently ignore miptree_create_for_bo's request for a tiled miptree. This results in some parts of mesa treating the surface as tiled and other parts of treating the surface as linear. I couldn't come up with a piglit test for this when I was working on a fix. Please let me know if you can think of any. I think what the limits should be depends on which mesa branch you're working off of. * On the master branch of mesa, which has some commits which reduce the dependence on the BLT engine, we can remove these limits by using BLORP. As much as I can tell, BLORP can handle images as wide as the surface pitch limit in the RENDER_SURFACE_STATE packet will allow. I sent out a series [a] a couple weeks ago that removes the limits imposed by the hardware blitter. * On the stable branch however, we can modify some incorrect code to set the correct BLT limits (as Chris has suggested). The BLT engine's pitch field is a signed 16bit integer, whose unit changes depending on the tiling of the surface. For linear surfaces, it's in units of bytes and for non-linear surfaces, it's in units of dwords. This translates to 2^15-1 bytes or (2^15-1) * 4 bytes respectively. I made a branch [b] which does this already, but I think my rebasing + testing strategy for stable branches on the CI might be incorrect. [a] https://patchwork.freedesktop.org/series/43971/ [b] https://cgit.freedesktop.org/~nchery/mesa/log/?h=wip/stable/stop-retiling > Tested-by: Martin Peres <martin.pe...@linux.intel.com> # HSW > Cc: Chris Wilson <ch...@chris-wilson.co.uk> > > [1] https://fs.mupuf.org/corruption_8k%2B.png > --- > src/mesa/drivers/dri/i965/intel_blit.c | 2 +- > src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 4 ++-- > 2 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/src/mesa/drivers/dri/i965/intel_blit.c > b/src/mesa/drivers/dri/i965/intel_blit.c > index 90784c5b1958..458f8bd42857 100644 > --- a/src/mesa/drivers/dri/i965/intel_blit.c > +++ b/src/mesa/drivers/dri/i965/intel_blit.c > @@ -403,7 +403,7 @@ emit_miptree_blit(struct brw_context *brw, > * for linear surfaces and DWords for tiled surfaces. So the maximum > * pitch is 32k linear and 128k tiled. > */ > - if (blt_pitch(src_mt) >= 32768 || blt_pitch(dst_mt) >= 32768) { > + if (blt_pitch(src_mt) >= 65536 || blt_pitch(dst_mt) >= 65536) { This is too large for linear miptrees. > perf_debug("Falling back due to >= 32k/128k pitch\n"); > return false; > } > diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c > b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c > index 6b89bf6848af..7347ea8b99d8 100644 > --- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c > +++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c > @@ -523,7 +523,7 @@ need_to_retile_as_linear(struct brw_context *brw, > unsigned row_pitch, > if (row_pitch < 64) > return true; > > - if (ALIGN(row_pitch, 512) >= 32768) { > + if (ALIGN(row_pitch, 512) >= 65536) { > perf_debug("row pitch %u too large to blit, falling back to untiled", > row_pitch); > return true; > @@ -3583,7 +3583,7 @@ can_blit_slice(struct intel_mipmap_tree *mt, > unsigned int level, unsigned int slice) > { > /* See intel_miptree_blit() for details on the 32k pitch limit. */ > - if (mt->surf.row_pitch >= 32768) > + if (mt->surf.row_pitch >= 65536) This is also too large for linear miptrees. -Nanley > > return true; > -- > 2.17.1 > > _______________________________________________ > mesa-dev mailing list > mesa-dev@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/mesa-dev _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
