drm/i915: Round tile chunks up for constructing partial VMAs

When we split a large object up into chunks for GTT faulting (because we
can't fit the whole object into the aperture) we have to align our cuts
with the fence registers. Each partial VMA must cover a complete set of
tile rows or the offset into each partial VMA is not aligned with the
whole image. Currently we enforce a minimum size on each partial VMA,
but this minimum size itself was not aligned to the tile row causing
distortion.

Reported-by: Andreas Reis <andreas.reis@gmail.com>
Reported-by: Chris Clayton <chris2553@googlemail.com>
Reported-by: Norbert Preining <preining@logic.at>
Tested-by: Norbert Preining <preining@logic.at>
Tested-by: Chris Clayton <chris2553@googlemail.com>
Fixes: 03af84fe7f48 ("drm/i915: Choose partial chunksize based on tile row size")
Fixes: a61007a83a46 ("drm/i915: Fix partial GGTT faulting") # enabling patch
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98402
Testcase: igt/gem_mmap_gtt/medium-copy-odd
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: <drm-intel-fixes@lists.freedesktop.org> # v4.9-rc1+
Link: http://patchwork.freedesktop.org/patch/msgid/20161107105443.27855-1-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0dbf38c51d14908ce722d421f6b2fcbf9a3bd16d..33445ffba2c063bc3076c8f86caadf118bc89438 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1779,7 +1779,7 @@ int i915_gem_fault(struct vm_area_struct *area, struct vm_fault *vmf)
                /* Use a partial view if it is bigger than available space */
                chunk_size = MIN_CHUNK_PAGES;
                if (i915_gem_object_is_tiled(obj))
-                       chunk_size = max(chunk_size, tile_row_pages(obj));
+                       chunk_size = roundup(chunk_size, tile_row_pages(obj));
 
                memset(&view, 0, sizeof(view));
                view.type = I915_GGTT_VIEW_PARTIAL;