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* [PATCH] iommu/arm-smmu: fix "hang" when games exit
@ 2019-09-07 17:50 Rob Clark
  2019-09-10 15:01 ` Robin Murphy
  0 siblings, 1 reply; 9+ messages in thread
From: Rob Clark @ 2019-09-07 17:50 UTC (permalink / raw)
  To: iommu
  Cc: Rob Clark, Will Deacon, linux-arm-msm, Robin Murphy, open list,
	freedreno, 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 is 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>
---
Note: I've tied the autosuspend enable/delay to the consumer device,
based on the reasoning that if the consumer device benefits from using
an autosuspend delay, then it's corresponding SMMU probably does too.
Maybe that is overkill and we should just unconditionally enable
autosuspend.

 drivers/iommu/arm-smmu.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index c2733b447d9c..73a0dd53c8a3 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -289,7 +289,7 @@ 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)
@@ -1445,6 +1445,15 @@ 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);
 
+#ifdef CONFIG_PM
+	/* TODO maybe device_link_add() should do this for us? */
+	if (dev->power.use_autosuspend) {
+		pm_runtime_set_autosuspend_delay(smmu->dev,
+			dev->power.autosuspend_delay);
+		pm_runtime_use_autosuspend(smmu->dev);
+	}
+#endif
+
 rpm_put:
 	arm_smmu_rpm_put(smmu);
 	return ret;
-- 
2.21.0

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^ permalink raw reply	[flat|nested] 9+ messages in thread

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Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-09-07 17:50 [PATCH] iommu/arm-smmu: fix "hang" when games exit Rob Clark
2019-09-10 15:01 ` Robin Murphy
2019-09-10 15:45   ` Rob Clark
2019-10-07 20:49   ` [PATCH v2] " Rob Clark
2019-10-09 10:10     ` Robin Murphy
2019-10-28 22:20     ` Will Deacon
2019-10-28 22:38       ` Rob Clark
2019-10-28 22:51         ` Robin Murphy
2019-10-29 11:15           ` Will Deacon

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