diff options
| author | Rob Clark <robdclark@chromium.org> | 2019-10-31 14:31:02 -0700 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2019-11-01 16:28:39 +0000 |
| commit | ee9bdfedd3dc1b3303390663189defa4d6b9e458 (patch) | |
| tree | d48cda4b64c38e39a5e4fab236a6f2fead10918f /drivers/iommu | |
| parent | bdde4718aba368c33705ccff8f3e29586d41b69b (diff) | |
| download | linux-ee9bdfedd3dc1b3303390663189defa4d6b9e458.tar.bz2 | |
iommu/arm-smmu: Avoid pathological RPM behaviour for unmaps
When games, browser, or anything using a lot of GPU buffers exits, there
can be many hundreds or thousands of buffers to unmap and free. If the
GPU is otherwise suspended, this can cause arm-smmu to resume/suspend
for each buffer, resulting 5-10 seconds worth of reprogramming the
context bank (arm_smmu_write_context_bank()/arm_smmu_write_s2cr()/etc).
To the user it would appear that the system just locked up.
A simple solution is to use pm_runtime_put_autosuspend() instead, so we
don't immediately suspend the SMMU device.
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'drivers/iommu')
| -rw-r--r-- | drivers/iommu/arm-smmu.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index 080af0326816..a2b1ca55b73e 100644 --- a/drivers/iommu/arm-smmu.c +++ b/drivers/iommu/arm-smmu.c @@ -123,7 +123,7 @@ static inline int arm_smmu_rpm_get(struct arm_smmu_device *smmu) static inline void arm_smmu_rpm_put(struct arm_smmu_device *smmu) { if (pm_runtime_enabled(smmu->dev)) - pm_runtime_put(smmu->dev); + pm_runtime_put_autosuspend(smmu->dev); } static struct arm_smmu_domain *to_smmu_domain(struct iommu_domain *dom) @@ -1167,6 +1167,20 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev) /* Looks ok, so add the device to the domain */ ret = arm_smmu_domain_add_master(smmu_domain, fwspec); + /* + * Setup an autosuspend delay to avoid bouncing runpm state. + * Otherwise, if a driver for a suspended consumer device + * unmaps buffers, it will runpm resume/suspend for each one. + * + * For example, when used by a GPU device, when an application + * or game exits, it can trigger unmapping 100s or 1000s of + * buffers. With a runpm cycle for each buffer, that adds up + * to 5-10sec worth of reprogramming the context bank, while + * the system appears to be locked up to the user. + */ + pm_runtime_set_autosuspend_delay(smmu->dev, 20); + pm_runtime_use_autosuspend(smmu->dev); + rpm_put: arm_smmu_rpm_put(smmu); return ret; |