[PATCH v10 06/15] iommu/tegra241-cmdqv: Restore PROD and CONS after resume
From: Pranjal Shrivastava <praan@google.com>
Date: 2026-09-08 17:17:30
Also in:
driver-core, linux-iommu
Subsystem:
arm smmu drivers, iommu subsystem, tegra iommu drivers, the rest · Maintainers:
Will Deacon, Joerg Roedel, Thierry Reding, Linus Torvalds
From: Ashish Mhetre <redacted> PROD and CONS indices for vcmdqs are getting set to 0 after resume. Because of this the vcmdq is not consuming commands after resume. Fix this by restoring PROD and CONS indices after resume from saved pointers. Reviewed-by: Nicolin Chen <redacted> Signed-off-by: Ashish Mhetre <redacted> Signed-off-by: Pranjal Shrivastava <praan@google.com> --- drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
index a394bf0f487f..c7989fcd2c62 100644
--- a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
+++ b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c@@ -567,6 +567,16 @@ static int tegra241_vcmdq_hw_init(struct tegra241_vcmdq *vcmdq) /* Configure and enable VCMDQ */ writeq_relaxed(vcmdq->cmdq.q.q_base, REG_VCMDQ_PAGE1(vcmdq, BASE)); + /* + * HW Registers reset to 0 when power-cycled. Restore them from their + * SW copies to prevent executing stale/ghost commands after resume. + * Note on RPM: Power-cycles can never happen when VCMDQs are assigned + * to the Guests since the relevant frameworks (IOMMUFD / VFIO) hold + * active PM references preventing suspend while VMs are active. + */ + writel_relaxed(vcmdq->cmdq.q.llq.prod, REG_VCMDQ_PAGE0(vcmdq, PROD)); + writel_relaxed(vcmdq->cmdq.q.llq.cons, REG_VCMDQ_PAGE0(vcmdq, CONS)); + ret = vcmdq_write_config(vcmdq, VCMDQ_EN); if (ret) { dev_err(vcmdq->cmdqv->dev,
--
2.55.0.979.g7e5102b832-goog