2 files changed, 29 insertions, 6 deletions

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 8966f7d5a..82f100e59 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -152,6 +152,18 @@ static void queue_inc_cons(struct arm_smmu_ll_queue *q)
 	q->cons = Q_OVF(q->cons) | Q_WRP(q, cons) | Q_IDX(q, cons);
 }
 
+static void queue_sync_cons_ovf(struct arm_smmu_queue *q)
+{
+	struct arm_smmu_ll_queue *llq = &q->llq;
+
+	if (likely(Q_OVF(llq->prod) == Q_OVF(llq->cons)))
+		return;
+
+	llq->cons = Q_OVF(llq->prod) | Q_WRP(llq, llq->cons) |
+		      Q_IDX(llq, llq->cons);
+	queue_sync_cons_out(q);
+}
+
 static int queue_sync_prod_in(struct arm_smmu_queue *q)
 {
 	u32 prod;
@@ -1583,8 +1595,7 @@ static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev)
 	} while (!queue_empty(llq));
 
 	/* Sync our overflow flag, as we believe we're up to speed */
-	llq->cons = Q_OVF(llq->prod) | Q_WRP(llq, llq->cons) |
-		    Q_IDX(llq, llq->cons);
+	queue_sync_cons_ovf(q);
 	return IRQ_HANDLED;
 }
 
@@ -1642,9 +1653,7 @@ static irqreturn_t arm_smmu_priq_thread(int irq, void *dev)
 	} while (!queue_empty(llq));
 
 	/* Sync our overflow flag, as we believe we're up to speed */
-	llq->cons = Q_OVF(llq->prod) | Q_WRP(llq, llq->cons) |
-		      Q_IDX(llq, llq->cons);
-	queue_sync_cons_out(q);
+	queue_sync_cons_ovf(q);
 	return IRQ_HANDLED;
 }
 
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
index d80065c81..f15dcb9e4 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
@@ -267,13 +267,27 @@ static int qcom_smmu_init_context(struct arm_smmu_domain *smmu_domain,
 
 static int qcom_smmu_cfg_probe(struct arm_smmu_device *smmu)
 {
-	unsigned int last_s2cr = ARM_SMMU_GR0_S2CR(smmu->num_mapping_groups - 1);
 	struct qcom_smmu *qsmmu = to_qcom_smmu(smmu);
+	unsigned int last_s2cr;
 	u32 reg;
 	u32 smr;
 	int i;
 
 	/*
+	 * Some platforms support more than the Arm SMMU architected maximum of
+	 * 128 stream matching groups. For unknown reasons, the additional
+	 * groups don't exhibit the same behavior as the architected registers,
+	 * so limit the groups to 128 until the behavior is fixed for the other
+	 * groups.
+	 */
+	if (smmu->num_mapping_groups > 128) {
+		dev_notice(smmu->dev, "\tLimiting the stream matching groups to 128\n");
+		smmu->num_mapping_groups = 128;
+	}
+
+	last_s2cr = ARM_SMMU_GR0_S2CR(smmu->num_mapping_groups - 1);
+
+	/*
 	 * With some firmware versions writes to S2CR of type FAULT are
 	 * ignored, and writing BYPASS will end up written as FAULT in the
 	 * register. Perform a write to S2CR to detect if this is the case and