drm/i915: Overcome display engine stride limits via GTT remapping
The display engine stride limits are getting in our way. On SKL+ we are limited to 8k pixels, which is easily exceeded with three 4k displays. To overcome this limitation we can remap the pages in the GTT to provide the display engine with a view of memory with a smaller stride. The code is mostly already there as We already play tricks with the plane surface address and x/y offsets. A few caveats apply: * linear buffers need the fb stride to be page aligned, as otherwise the remapped lines wouldn't start at the same spot * compressed buffers can't be remapped due to the new ccs hash mode causing the virtual address of the pages to affect the interpretation of the compressed data. IIRC the old hash was limited to the low 12 bits so if we were using that mode we could remap. As it stands we just refuse to remapp with compressed fbs. * no remapping gen2/3 as we'd need a fence for the remapped vma, which we currently don't have. Need to deal with the fence POT requirements, and do something about the gen2 gtt page size vs tile size difference v2: Rebase due to is_ccs_modifier() Fix up the skl+ stride_mult mess memset() the gtt_view because otherwise we could leave junk in plane[1] when going from 2 plane to 1 plane format v3: intel_check_plane_stride() was split out v4: Drop the aligned viewport stuff, it was meant for ccs which can't be remapped anyway v5: Introduce intel_plane_can_remap() Reorder the code so that plane_state->view gets filled even for invisible planes, otherwise we'd keep using stale values and could explode during remapping. The new logic never remaps invisible planes since we don't have a viewport, and instead pins the full fb instead v6: Fix plane src coord checks after remapping by moving plane_state->base.src to the final plane x/y offsets. Allow intel_plane_check_stride() to fail even with remapping (can happen at least with a linear 64bpp fb with a 4k plane and a suitably inconvenient src coordinates). Improve aux plane FIXME (Daniel) Move some code shuffling into a separate patch (Daniel) Testcase: igt/kms_big_fb Cc: Daniel Vetter <daniel@ffwll.ch> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190509122159.24376-6-ville.syrjala@linux.intel.comReviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
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