Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S968479AbdD0LNn (ORCPT ); Thu, 27 Apr 2017 07:13:43 -0400 Received: from mail-pf0-f193.google.com ([209.85.192.193]:36357 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966732AbdD0LNj (ORCPT ); Thu, 27 Apr 2017 07:13:39 -0400 From: sunil.kovvuri@gmail.com To: will.deacon@arm.com, robin.murphy@arm.com, iommu@lists.linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, robert.richter@cavium.com, jcm@redhat.com, Sunil Goutham , Geetha 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> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1863 Lines: 58 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