From: Pranjal Shrivastava <praan@google•com>
To: Daniel Mentz <danielmentz@google•com>
Cc: iommu@lists•linux.dev, Will Deacon <will@kernel•org>,
Joerg Roedel <joro@8bytes•org>,
Robin Murphy <robin.murphy@arm•com>,
Jason Gunthorpe <jgg@ziepe•ca>,
Mostafa Saleh <smostafa@google•com>,
Nicolin Chen <nicolinc@nvidia•com>,
Ashish Mhetre <amhetre@nvidia•com>,
linux-arm-kernel@lists•infradead.org
Subject: Re: [PATCH v8 09/12] iommu/arm-smmu-v3: Implement pm_runtime & system sleep ops
Date: Tue, 2 Jun 2026 12:12:16 +0000 [thread overview]
Message-ID: <ah7IoJqmRbK7xK5-@google.com> (raw)
In-Reply-To: <CAE2F3rAYWMq6DO5k20e4iMtPbh_X9JeiU8kUfw8nsS5xs42F_Q@mail.gmail.com>
On Mon, Jun 01, 2026 at 10:25:41PM -0700, Daniel Mentz wrote:
> On Mon, Jun 1, 2026 at 2:59 PM Pranjal Shrivastava <praan@google•com> wrote:
>
> > + /* Drain the CMDQs */
> > + ret = arm_smmu_drain_queues(smmu);
> > + if (ret)
> > + dev_warn(smmu->dev, "failed to drain queues, forcing suspend\n");
>
> Can arm_smmu_drain_queues() be called after cmdq->lock is 0? I think
> that way we can be sure that no other thread updates smmu->cmdq.q.cons
>
Hmm.. that wouldn't work for impl-specific CMDQs as we STOP and drain
them together in a single function.. maybe I'll factor out setting the
STOP_FLAG on impl-specific queues as another impl_op, gate the queues
first, wait for lock == 0 and then drain_queues?
> > +
> > + /* Wait for cmdq->lock == 0 to ensure last CMDQ_CONS_REG is written */
> > + timeout = ARM_SMMU_SUSPEND_TIMEOUT_US;
> > + while (atomic_read(&cmdq->lock) != 0 && --timeout)
> > + udelay(1);
> > +
> > + /* Timing out here implies misconfigured Runtime PM or broken devlinks */
> > + if (!timeout)
> > + dev_err(smmu->dev, "cmdq lock != 0, forcing suspend. Polling CPUs may fault.\n");
Thanks,
Praan
next prev parent reply other threads:[~2026-06-02 12:12 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-01 21:58 [PATCH v8 00/10] iommu/arm-smmu-v3: Implement Runtime/System Sleep ops Pranjal Shrivastava
2026-06-01 21:58 ` [PATCH v8 01/12] iommu/arm-smmu-v3: Refactor arm_smmu_setup_irqs Pranjal Shrivastava
2026-06-01 21:58 ` [PATCH v8 02/12] iommu/arm-smmu-v3: Add a helper to drain cmd queues Pranjal Shrivastava
2026-06-02 0:12 ` Nicolin Chen
2026-06-02 3:28 ` Pranjal Shrivastava
2026-06-02 5:21 ` Daniel Mentz
2026-06-01 21:59 ` [PATCH v8 03/12] iommu/tegra241-cmdqv: Add a helper to drain VCMDQs Pranjal Shrivastava
2026-06-01 21:59 ` [PATCH v8 04/12] iommu/tegra241-cmdqv: Restore PROD and CONS after resume Pranjal Shrivastava
2026-06-01 21:59 ` [PATCH v8 05/12] iommu/arm-smmu-v3: Cache and restore MSI config Pranjal Shrivastava
2026-06-01 21:59 ` [PATCH v8 06/12] iommu/arm-smmu-v3: Handle gerror during suspend Pranjal Shrivastava
2026-06-02 0:15 ` Nicolin Chen
2026-06-02 3:31 ` Pranjal Shrivastava
2026-06-01 21:59 ` [PATCH v8 07/12] iommu/arm-smmu-v3: Add CMDQ_PROD_STOP_FLAG to gate CMDQ submissions Pranjal Shrivastava
2026-06-01 21:59 ` [PATCH v8 08/12] iommu/tegra241-cmdqv: Add a helper to quiesce VCMDQs Pranjal Shrivastava
2026-06-02 0:14 ` Nicolin Chen
2026-06-02 3:37 ` Pranjal Shrivastava
2026-06-02 5:59 ` Nicolin Chen
2026-06-02 6:21 ` Pranjal Shrivastava
2026-06-02 6:29 ` Nicolin Chen
2026-06-01 21:59 ` [PATCH v8 09/12] iommu/arm-smmu-v3: Implement pm_runtime & system sleep ops Pranjal Shrivastava
2026-06-02 5:25 ` Daniel Mentz
2026-06-02 12:12 ` Pranjal Shrivastava [this message]
2026-06-02 15:27 ` Daniel Mentz
2026-06-01 21:59 ` [PATCH v8 10/12] iommu/arm-smmu-v3: Enable pm_runtime and setup devlinks Pranjal Shrivastava
2026-06-01 21:59 ` [PATCH v8 11/12] iommu/arm-smmu-v3: Invoke pm_runtime before hw access Pranjal Shrivastava
2026-06-02 0:24 ` Nicolin Chen
2026-06-02 3:59 ` Pranjal Shrivastava
2026-06-02 5:51 ` Nicolin Chen
2026-06-02 6:24 ` Pranjal Shrivastava
2026-06-03 20:28 ` Daniel Mentz
2026-06-04 6:27 ` Pranjal Shrivastava
2026-06-01 21:59 ` [PATCH v8 12/12] iommu/arm-smmu-v3: Add KUnit unit tests for Runtime PM Pranjal Shrivastava
2026-06-02 6:03 ` [PATCH v8 00/10] iommu/arm-smmu-v3: Implement Runtime/System Sleep ops Nicolin Chen
2026-06-02 12:04 ` Pranjal Shrivastava
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