From: Dmitry Osipenko digetx@gmail.com
commit 61b51fb51c01a519a249d28ec55c6513a13be5a3 upstream.
The allocated pages need to be invalidated in CPU caches. On ARM32 the DMA_BIDIRECTIONAL flag only ensures that data is written-back to DRAM and the data stays in CPU cache lines. While the DMA_FROM_DEVICE flag ensures that the corresponding CPU cache lines are getting invalidated and nothing more, that's exactly what is needed for a newly allocated pages.
This fixes randomly failing rendercheck tests on Tegra30 using the Opentegra driver for tests that use small-sized pixmaps (10x10 and less, i.e. 1-2 memory pages) because apparently CPU reads out stale data from caches and/or that data is getting evicted to DRAM at the time of HW job execution.
Fixes: bd43c9f0fa1f ("drm/tegra: gem: Map pages via the DMA API") Cc: stable stable@vger.kernel.org Signed-off-by: Dmitry Osipenko digetx@gmail.com Signed-off-by: Thierry Reding treding@nvidia.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/gpu/drm/tegra/gem.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/gpu/drm/tegra/gem.c +++ b/drivers/gpu/drm/tegra/gem.c @@ -204,7 +204,7 @@ static void tegra_bo_free(struct drm_dev { if (bo->pages) { dma_unmap_sg(drm->dev, bo->sgt->sgl, bo->sgt->nents, - DMA_BIDIRECTIONAL); + DMA_FROM_DEVICE); drm_gem_put_pages(&bo->gem, bo->pages, true, true); sg_free_table(bo->sgt); kfree(bo->sgt); @@ -230,7 +230,7 @@ static int tegra_bo_get_pages(struct drm }
err = dma_map_sg(drm->dev, bo->sgt->sgl, bo->sgt->nents, - DMA_BIDIRECTIONAL); + DMA_FROM_DEVICE); if (err == 0) { err = -EFAULT; goto free_sgt;