[PATCH v2] iommu/arm-smmu-v3: Increase CMDQ drain timeout value
Sunil Kovvuri
sunil.kovvuri at gmail.com
Mon May 29 02:11:59 PDT 2017
On Fri, May 5, 2017 at 4:47 PM, <sunil.kovvuri at gmail.com> wrote:
> From: Sunil Goutham <sgoutham at cavium.com>
>
> Processing queue full of TLB invalidation commands might
> take more time on some platforms than current timeout
> of 100us. So increased drain timeout value.
>
> Also now udelay time is increased exponentially for each poll.
>
> Signed-off-by: Sunil Goutham <sgoutham at cavium.com>
> ---
>
> v2
> - Addressed Will's and Robin's comments i.e
> increased poll timeout only for drain case and removed spin loop
> whose logic anyway is screwed up.
> - Also changed commit subject and message as this patch no longer
> exactly reflects what is done in SMMU driver i.e
> 8513c8930069 iommu/arm-smmu: Poll for TLB sync completion more effectively
>
> drivers/iommu/arm-smmu-v3.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> index d412bdd..cbc8309 100644
> --- a/drivers/iommu/arm-smmu-v3.c
> +++ b/drivers/iommu/arm-smmu-v3.c
> @@ -379,6 +379,8 @@
> #define CMDQ_SYNC_0_CS_NONE (0UL << CMDQ_SYNC_0_CS_SHIFT)
> #define CMDQ_SYNC_0_CS_SEV (2UL << CMDQ_SYNC_0_CS_SHIFT)
>
> +#define CMDQ_DRAIN_TIMEOUT_US 1000
> +
> /* Event queue */
> #define EVTQ_ENT_DWORDS 4
> #define EVTQ_MAX_SZ_SHIFT 7
> @@ -737,7 +739,12 @@ 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 ? 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 +754,11 @@ static int queue_poll_cons(struct arm_smmu_queue *q, bool drain, bool wfe)
> wfe();
> } else {
> cpu_relax();
> - udelay(1);
> + udelay(delay);
> + /* No point in sleeping for fixed time,
> + * if cons isn't moving fast.
> + */
> + delay *= 2;
> }
> }
>
> --
> 2.7.4
>
Gentle reminder for patch review.
Thanks,
Sunil.
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