From mboxrd@z Thu Jan 1 00:00:00 1970 From: sunil.kovvuri-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org Subject: [PATCH] iommu/arm-smmu-v3: Poll for CMDQ drain completion more effectively Date: Thu, 27 Apr 2017 16:43:07 +0530 Message-ID: <1493291587-23488-1-git-send-email-sunil.kovvuri@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: will.deacon-5wv7dgnIgG8@public.gmane.org, robin.murphy-5wv7dgnIgG8@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Cc: jcm-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, robert.richter-YGCgFSpz5w/QT0dZR+AlfA@public.gmane.org, Geetha , Sunil Goutham , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: iommu@lists.linux-foundation.org From: Sunil Goutham Modified polling on CMDQ consumer similar to how polling is done for TLB SYNC completion in SMMUv2 driver. Code changes are done with reference to 8513c8930069 iommu/arm-smmu: Poll for TLB sync completion more effectively Poll timeout has been increased which addresses issue of 100us timeout not sufficient, when command queue is full with TLB invalidation commands. Signed-off-by: Sunil Goutham Signed-off-by: Geetha --- drivers/iommu/arm-smmu-v3.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c index d412bdd..34599d4 100644 --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -379,6 +379,9 @@ #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 +#define CMDQ_SPIN_COUNT 10 + /* Event queue */ #define EVTQ_ENT_DWORDS 4 #define EVTQ_MAX_SZ_SHIFT 7 @@ -737,7 +740,8 @@ 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 = ktime_add_us(ktime_get(), CMDQ_DRAIN_TIMEOUT_US); + unsigned int spin_cnt, delay = 1; while (queue_sync_cons(q), (drain ? !queue_empty(q) : queue_full(q))) { if (ktime_compare(ktime_get(), timeout) > 0) @@ -746,8 +750,13 @@ static int queue_poll_cons(struct arm_smmu_queue *q, bool drain, bool wfe) if (wfe) { wfe(); } else { - cpu_relax(); - udelay(1); + for (spin_cnt = 0; + spin_cnt < CMDQ_SPIN_COUNT; spin_cnt++) { + cpu_relax(); + continue; + } + udelay(delay); + delay *= 2; } } -- 2.7.4