From: Nicolin Chen <nicolinc@nvidia•com>
To: Pranjal Shrivastava <praan@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>,
Daniel Mentz <danielmentz@google•com>,
Ashish Mhetre <amhetre@nvidia•com>,
<linux-arm-kernel@lists•infradead.org>
Subject: Re: [PATCH v8 11/12] iommu/arm-smmu-v3: Invoke pm_runtime before hw access
Date: Mon, 1 Jun 2026 22:51:34 -0700 [thread overview]
Message-ID: <ah5vZl3zcC6YPeZ5@Asurada-Nvidia> (raw)
In-Reply-To: <ah5VOE5vuEPwr4oQ@google.com>
On Tue, Jun 02, 2026 at 03:59:52AM +0000, Pranjal Shrivastava wrote:
> On Mon, Jun 01, 2026 at 05:24:18PM -0700, Nicolin Chen wrote:
> > On Mon, Jun 01, 2026 at 09:59:08PM +0000, Pranjal Shrivastava wrote:
> > > -static inline bool arm_smmu_can_elide(struct arm_smmu_device *smmu)
> > > +static inline bool arm_smmu_cmdq_can_elide(struct arm_smmu_device *smmu)
> > > {
> > > return !!Q_STOP(READ_ONCE(smmu->cmdq.q.llq.prod));
> > > }
> >
> > Can it be named perfectly at the beginning?
>
> Ack.
>
> >
> > And again, should it check Q_STOP in vcmdq?
>
> I don't think so.. the primary CMDQ's STOP_FLAG should act as a proxy for
> the SMMU's global power state. Since all queues (primary and secondary)
> are gated synchronously during suspend after SMMUEN=0, and ungated before
> SMMUEN=1 (i.e.before the caching can begin). Checking the primary queue
> should suffice..
Should leave a note inline to elaborate why we only check primary
cmdq only.
[...]
> We can also decide to drop the can_elide checks from invs_array and
> atc_inv_master altogether, leaving gerror & page_response the only
> remaining call-sites, both of which don't use secondary queues.
That's not true.. In the host mode, any command will be issued to
vcmdq. IOW, primary queue might not be used at all.
Nicolin
next prev parent reply other threads:[~2026-06-02 5:52 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
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 [this message]
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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