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[94.29.37.86]) by smtp.gmail.com with ESMTPSA id a196sm4833lfa.89.2019.03.06.14.57.02 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 06 Mar 2019 14:57:02 -0800 (PST) From: Dmitry Osipenko To: Thierry Reding , Jonathan Hunter Cc: dri-devel@lists.freedesktop.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v1] drm/tegra: gem: Fix CPU-cache maintenance for BO's allocated using get_pages() Date: Thu, 7 Mar 2019 01:55:19 +0300 Message-Id: <20190306225519.4538-1-digetx@gmail.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Cc: stable Signed-off-by: Dmitry Osipenko --- drivers/gpu/drm/tegra/gem.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c index 4f80100ff5f3..4cce11fd8836 100644 --- 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_device *drm, struct tegra_bo *bo) { 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_device *drm, struct tegra_bo *bo) } 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; -- 2.20.1