Re: [PATCH] iommu/arm-smmu-v3: Increase SMMU CMD queue poll timeout

Will Deacon
2017-04-24T16:08:52Z

On Mon, Apr 24, 2017 at 05:29:36PM +0530, Geetha sowjanya wrote:
> From: Geetha <gakula@cavium.com>
>
> When large memory is being unmapped, huge no of tlb invalidation cmds are
> submitted followed by a SYNC command. This sometimes hits CMD queue full and
> poll on queue drain is being timedout throwing error message 'CMD_SYNC timeout'.
>
> Although there is no functional issue, error message confuses user. Hence increased
> poll timeout to 500us

Hmm, what are you doing to unmap that much? Is this VFIO teardown? Do you
have 7c6d90e2bb1a ("iommu/io-pgtable-arm: Fix iova_to_phys for block
entries") applied?

Will

>
> Signed-off-by: Geetha <gakula@cavium.com>
> ---
> drivers/iommu/arm-smmu-v3.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> index 591bb96..1dcd154 100644
> --- a/drivers/iommu/arm-smmu-v3.c
> +++ b/drivers/iommu/arm-smmu-v3.c
> @@ -407,7 +407,7 @@
> #define PRIQ_1_ADDR_MASK 0xfffffffffffffUL
>
> /* High-level queue structures */
> -#define ARM_SMMU_POLL_TIMEOUT_US 100
> +#define ARM_SMMU_POLL_TIMEOUT_US 500
>
> #define MSI_IOVA_BASE 0x8000000
> #define MSI_IOVA_LENGTH 0x100000
> --
> 1.9.1
>