* [PATCH] iommu/arm-smmu: avoid pathological RPM behaviour for unmaps
@ 2019-10-31 21:31 Rob Clark
2019-11-01 16:28 ` Will Deacon
0 siblings, 1 reply; 2+ messages in thread
From: Rob Clark @ 2019-10-31 21:31 UTC (permalink / raw)
To: iommu
Cc: Rob Clark, Will Deacon, freedreno, open list, linux-arm-msm,
Robin Murphy, moderated list:ARM SMMU DRIVERS
From: Rob Clark <robdclark@chromium.org>
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.
Signed-off-by: Rob Clark <robdclark@chromium.org>
---
drivers/iommu/arm-smmu.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 7c503a6bc585..5abc0d210d90 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -122,7 +122,7 @@ 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)
@@ -1154,6 +1154,20 @@ 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 suspendend 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;
--
2.21.0
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] iommu/arm-smmu: avoid pathological RPM behaviour for unmaps
2019-10-31 21:31 [PATCH] iommu/arm-smmu: avoid pathological RPM behaviour for unmaps Rob Clark
@ 2019-11-01 16:28 ` Will Deacon
0 siblings, 0 replies; 2+ messages in thread
From: Will Deacon @ 2019-11-01 16:28 UTC (permalink / raw)
To: Rob Clark
Cc: Rob Clark, Robin Murphy, open list, iommu, linux-arm-msm,
freedreno, moderated list:ARM SMMU DRIVERS
On Thu, Oct 31, 2019 at 02:31:02PM -0700, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
>
> 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.
>
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
> drivers/iommu/arm-smmu.c | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 7c503a6bc585..5abc0d210d90 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -122,7 +122,7 @@ 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)
> @@ -1154,6 +1154,20 @@ 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 suspendend consumer device
I fixed this typo and applied with Robin's reviewed-by from before.
Will
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2019-11-01 16:28 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-10-31 21:31 [PATCH] iommu/arm-smmu: avoid pathological RPM behaviour for unmaps Rob Clark
2019-11-01 16:28 ` Will Deacon
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).