iommu/arm-smmu-v3: Increase CMDQ drain timeout value

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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>

...

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Sunil Goutham 2017-05-05 16:47:46 +05:30 • committed by Will Deacon

parent 2ea659a9ef

commit b847de4e50

1 changed files with 10 additions and 2 deletions

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drivers/iommu/arm-smmu-v3.c

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