[PATCH 2/2] drm/panfrost: Use coherent pagetable walk on Juno

Robin Murphy robin.murphy at arm.com
Mon Sep 30 15:24:59 UTC 2019

Although going full "dma-coherent" ends badly due to GEM objects still
being forcibly mapped non-cacheable, we can at least take advantage of
Juno's ACE-lite integration to skip cache maintenance for pagetables.

CC: Rob Herring <robh at kernel.org>
CC: Tomeu Vizoso <tomeu.vizoso at collabora.com>
Signed-off-by: Robin Murphy <robin.murphy at arm.com>

This isn't really meant as a series, I'm just sending it together
with patch #1 for context.

 drivers/gpu/drm/panfrost/panfrost_mmu.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c
index bdd990568476..560439f63277 100644
--- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
@@ -365,6 +365,9 @@ int panfrost_mmu_pgtable_alloc(struct panfrost_file_priv *priv)
 		.iommu_dev	= pfdev->dev,
+	if (of_device_is_compatible(pfdev->dev->of_node, "arm,juno-mali"))
+		pfdev->mmu->pgtbl_cfg.coherent_walk = true;
 	mmu->pgtbl_ops = alloc_io_pgtable_ops(ARM_MALI_LPAE, &mmu->pgtbl_cfg,
 	if (!mmu->pgtbl_ops)

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