This is a note to let you know that I've just added the patch titled
gpu: host1x: Avoid trying to use GART on Tegra20
to the 6.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
gpu-host1x-avoid-trying-to-use-gart-on-tegra20.patch
and it can be found in the queue-6.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 30e93bd81c72da68126ef2b35ee2699b6199fada
Author: Robin Murphy <robin.murphy@xxxxxxx>
Date: Thu Oct 20 15:23:40 2022 +0100
gpu: host1x: Avoid trying to use GART on Tegra20
[ Upstream commit c2418f911a31a266af4fbaca998dc73d3676475a ]
Since commit c7e3ca515e78 ("iommu/tegra: gart: Do not register with
bus") quite some time ago, the GART driver has effectively disabled
itself to avoid issues with the GPU driver expecting it to work in ways
that it doesn't. As of commit 57365a04c921 ("iommu: Move bus setup to
IOMMU device registration") that bodge no longer works, but really the
GPU driver should be responsible for its own behaviour anyway. Make the
workaround explicit.
Reported-by: Jon Hunter <jonathanh@xxxxxxxxxx>
Suggested-by: Dmitry Osipenko <digetx@xxxxxxxxx>
Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
Tested-by: Jon Hunter <jonathanh@xxxxxxxxxx>
Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index 6748ec1e0005..a1f909dac89a 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -1093,6 +1093,10 @@ static bool host1x_drm_wants_iommu(struct host1x_device *dev)
struct host1x *host1x = dev_get_drvdata(dev->dev.parent);
struct iommu_domain *domain;
+ /* Our IOMMU usage policy doesn't currently play well with GART */
+ if (of_machine_is_compatible("nvidia,tegra20"))
+ return false;
+
/*
* If the Tegra DRM clients are backed by an IOMMU, push buffers are
* likely to be allocated beyond the 32-bit boundary if sufficient
diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
index 0cd3f97e7e49..f60ea24db0ec 100644
--- a/drivers/gpu/host1x/dev.c
+++ b/drivers/gpu/host1x/dev.c
@@ -292,6 +292,10 @@ static void host1x_setup_virtualization_tables(struct host1x *host)
static bool host1x_wants_iommu(struct host1x *host1x)
{
+ /* Our IOMMU usage policy doesn't currently play well with GART */
+ if (of_machine_is_compatible("nvidia,tegra20"))
+ return false;
+
/*
* If we support addressing a maximum of 32 bits of physical memory
* and if the host1x firewall is enabled, there's no need to enable
