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| author | Sunil Goutham <sgoutham@cavium.com> | 2017-05-05 13:17:46 +0200 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2017-06-23 18:57:56 +0200 |
| commit | b847de4e5087fc8577c38a697d14fd2a5ce93352 (patch) | |
| tree | bc37e0ec58a5e42cb4632308b23816730a5c726f /drivers/iommu/arm-smmu-v3.c | |
| parent | Linux 4.12-rc1 (diff) | |
| download | linux-b847de4e5087fc8577c38a697d14fd2a5ce93352.tar.xz linux-b847de4e5087fc8577c38a697d14fd2a5ce93352.zip | |
iommu/arm-smmu-v3: Increase CMDQ drain timeout value
Waiting for a CMD_SYNC to be processed involves waiting for the command
queue to drain, which can take an awful lot longer than waiting for a
single entry to become available. Consequently, the common timeout value
of 100us has been observed to be too short on some platforms when a
CMD_SYNC is issued into a queued full of TLBI commands.
This patch resolves the issue by using a different (1s) timeout when
waiting for the CMDQ to drain and using a simple back-off mechanism
when polling the cons pointer in the absence of WFE support.
Signed-off-by: Sunil Goutham <sgoutham@cavium.com>
[will: rewrote commit message and cosmetic changes]
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'drivers/iommu/arm-smmu-v3.c')
| -rw-r--r-- | drivers/iommu/arm-smmu-v3.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c index 380969aa60d5..6a06be7626db 100644 --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -408,6 +408,7 @@ /* High-level queue structures */ #define ARM_SMMU_POLL_TIMEOUT_US 100 +#define ARM_SMMU_CMDQ_DRAIN_TIMEOUT_US 1000000 /* 1s! */ #define MSI_IOVA_BASE 0x8000000 #define MSI_IOVA_LENGTH 0x100000 @@ -737,7 +738,13 @@ static void queue_inc_prod(struct arm_smmu_queue *q) */ static int queue_poll_cons(struct arm_smmu_queue *q, bool drain, bool wfe) { - ktime_t timeout = ktime_add_us(ktime_get(), ARM_SMMU_POLL_TIMEOUT_US); + ktime_t timeout; + unsigned int delay = 1; + + /* Wait longer if it's queue drain */ + timeout = ktime_add_us(ktime_get(), drain ? + ARM_SMMU_CMDQ_DRAIN_TIMEOUT_US : + ARM_SMMU_POLL_TIMEOUT_US); while (queue_sync_cons(q), (drain ? !queue_empty(q) : queue_full(q))) { if (ktime_compare(ktime_get(), timeout) > 0) @@ -747,7 +754,8 @@ static int queue_poll_cons(struct arm_smmu_queue *q, bool drain, bool wfe) wfe(); } else { cpu_relax(); - udelay(1); + udelay(delay); + delay *= 2; } } |