Subject: [PATCH v8 03/12] iommu/tegra241-cmdqv: Add a helper to drain VCMDQs

From: Pranjal Shrivastava <[email-masked]>
Date: Mon, 1 Jun 2026 21:59:00 +0000

The tegra241-cmdqv driver supports vCMDQs which need to be drained
before suspending the SMMU. The current driver implementation only uses
VINTF0 for vCMDQs owned by the kernel which need to be drained. Add a
helper that drains all the enabled vCMDQs under VINTF0.

Add another function ptr to arm_smmu_impl_ops to drain implementation
specified queues and call it within `arm_smmu_drain_queues`.

Reviewed-by: Nicolin Chen <[email-masked]>
Signed-off-by: Pranjal Shrivastava <[email-masked]>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   |  7 +++++
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |  1 +
 .../iommu/arm/arm-smmu-v3/tegra241-cmdqv.c    | 27 +++++++++++++++++++
 3 files changed, 35 insertions(+)

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 0e77ef1e4523..8682be5060ed 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -915,6 +915,13 @@ static int arm_smmu_drain_queues(struct arm_smmu_device *smmu)
 	 */
 	ret = arm_smmu_queue_poll_until_empty(smmu, &smmu->cmdq.q);
 
+	if (ret)
+		goto out;
+
+	/* Drain all implementation-specific queues */
+	if (smmu->impl_ops && smmu->impl_ops->drain_queues)
+		ret = smmu->impl_ops->drain_queues(smmu);
+out:
 	return ret;
 }
 
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
index c855ab4962ed..24d5e28eea88 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -885,6 +885,7 @@ struct arm_smmu_impl_ops {
 	size_t (*get_viommu_size)(enum iommu_viommu_type viommu_type);
 	int (*vsmmu_init)(struct arm_vsmmu *vsmmu,
 			  const struct iommu_user_data *user_data);
+	int (*drain_queues)(struct arm_smmu_device *smmu);
 };
 
 /* An SMMUv3 instance */
diff --git a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
index 67be62a6e764..cb1e75e4ee91 100644
--- a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
+++ b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
@@ -414,6 +414,32 @@ tegra241_cmdqv_get_cmdq(struct arm_smmu_device *smmu,
 	return &vcmdq->cmdq;
 }
 
+static int tegra241_cmdqv_drain_vintf0_lvcmdqs(struct arm_smmu_device *smmu)
+{
+	struct tegra241_cmdqv *cmdqv =
+		container_of(smmu, struct tegra241_cmdqv, smmu);
+	struct tegra241_vintf *vintf = cmdqv->vintfs[0];
+	int ret = 0;
+	u16 lidx;
+
+	/* Kernel only uses VINTF0. Return if it's disabled */
+	if (!READ_ONCE(vintf->enabled))
+		return 0;
+
+	for (lidx = 0; lidx < cmdqv->num_lvcmdqs_per_vintf; lidx++) {
+		struct tegra241_vcmdq *vcmdq = vintf->lvcmdqs[lidx];
+
+		if (!vcmdq || !READ_ONCE(vcmdq->enabled))
+			continue;
+
+		ret = arm_smmu_queue_poll_until_empty(smmu, &vcmdq->cmdq.q);
+		if (ret)
+			break;
+	}
+
+	return ret;
+}
+
 /* HW Reset Functions */
 
 /*
@@ -845,6 +871,7 @@ static struct arm_smmu_impl_ops tegra241_cmdqv_impl_ops = {
 	.get_secondary_cmdq = tegra241_cmdqv_get_cmdq,
 	.device_reset = tegra241_cmdqv_hw_reset,
 	.device_remove = tegra241_cmdqv_remove,
+	.drain_queues = tegra241_cmdqv_drain_vintf0_lvcmdqs,
 	/* For user-space use */
 	.hw_info = tegra241_cmdqv_hw_info,
 	.get_viommu_size = tegra241_cmdqv_get_vintf_size,
-- 
2.54.0.1013.g208068f2d8-goog