[PATCH v6 03/10] iommu/tegra241-cmdqv: Add a helper to drain VCMDQs

Pranjal Shrivastava
2026-04-14T19:47:20Z

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 <nicolinc@nvidia.com>
Signed-off-by: Pranjal Shrivastava <praan@google.com>
---
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 088a7d1c002b..e865a8aa2210 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -1024,6 +1024,13 @@ 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 47799d58d10c..001734bc3c7d 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -818,6 +818,7 @@ 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 83f6e9f6c51d..b3ed2149f72b 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.rc0.605.g598a273b03-goog