From: Pranjal Shrivastava <praan@google•com>
To: Nicolin Chen <nicolinc@nvidia•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 v7 05/11] iommu/arm-smmu-v3: Cache and restore MSI config
Date: Thu, 28 May 2026 21:57:04 +0000 [thread overview]
Message-ID: <ahi6MJaAene0ogY8@google.com> (raw)
In-Reply-To: <ahiLFoRk4xaxr2vn@Asurada-Nvidia>
On Thu, May 28, 2026 at 11:36:06AM -0700, Nicolin Chen wrote:
> On Wed, May 27, 2026 at 10:14:01PM +0000, Pranjal Shrivastava wrote:
> > The SMMU's MSI configuration registers (*_IRQ_CFGn) containing target
> > address, data and memory attributes lose their state when the SMMU is
> > powered down. We'll need to cache and restore their contents to ensure
> > that MSIs work after the system resumes.
> >
> > To address this, cache the original `msi_msg` within the `msi_desc`
> > when the configuration is first written by `arm_smmu_write_msi_msg`.
> > This primarily includes the target address and data since the memory
> > attributes are fixed.
> >
> > Introduce a new helper `arm_smmu_resume_msis` which will later be called
> > during the driver's resume callback. The helper would retrieve the
> > cached MSI message for each relevant interrupt (evtq, gerr, priq) via
> > get_cached_msi_msg & re-config the registers via arm_smmu_write_msi_msg.
> >
> > Signed-off-by: Pranjal Shrivastava <praan@google•com>
>
> Reviewed-by: Nicolin Chen <nicolinc@nvidia•com>
>
> > +static void arm_smmu_resume_msi(struct arm_smmu_device *smmu,
> > + unsigned int irq, const char *name)
> > +{
> > + struct msi_desc *desc;
> > + struct msi_msg msg;
> > +
> > + if (!irq)
> > + return;
> > +
> > + desc = irq_get_msi_desc(irq);
> > + if (!desc) {
> > + dev_err(smmu->dev, "Failed to resume msi: %s", name);
> > + return;
> > + }
> > +
> > + get_cached_msi_msg(irq, &msg);
>
> I wonder if we could use __get_cached_msi_msg() since we got desc?
We could've (and that's a nice suggestion), but unfortunately it
(__get_cached_msi_msg) is not exported via EXPORT_SYMBOL_GPL() :(
We could break modular builds as CONFIG_ARM_SMMU_V3 is tristate.
Let me know if you have a strong preference about exporting it, we can
add a patch in the next versions.
Thanks,
Praan
next prev parent reply other threads:[~2026-05-28 21:57 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-27 22:13 [PATCH v7 00/11] iommu/arm-smmu-v3: Implement Runtime/System Sleep ops Pranjal Shrivastava
2026-05-27 22:13 ` [PATCH v7 01/11] iommu/arm-smmu-v3: Refactor arm_smmu_setup_irqs Pranjal Shrivastava
2026-05-27 22:13 ` [PATCH v7 02/11] iommu/arm-smmu-v3: Add a helper to drain cmd queues Pranjal Shrivastava
2026-05-28 1:35 ` Nicolin Chen
2026-05-28 10:34 ` Pranjal Shrivastava
2026-05-28 22:09 ` Nicolin Chen
2026-05-29 14:32 ` Pranjal Shrivastava
2026-05-27 22:13 ` [PATCH v7 03/11] iommu/tegra241-cmdqv: Add a helper to drain VCMDQs Pranjal Shrivastava
2026-05-27 22:14 ` [PATCH v7 04/11] iommu/tegra241-cmdqv: Restore PROD and CONS after resume Pranjal Shrivastava
2026-05-28 18:14 ` Nicolin Chen
2026-05-27 22:14 ` [PATCH v7 05/11] iommu/arm-smmu-v3: Cache and restore MSI config Pranjal Shrivastava
2026-05-28 18:36 ` Nicolin Chen
2026-05-28 21:57 ` Pranjal Shrivastava [this message]
2026-05-28 22:03 ` Nicolin Chen
2026-05-27 22:14 ` [PATCH v7 06/11] iommu/arm-smmu-v3: Handle gerror during suspend Pranjal Shrivastava
2026-05-28 18:53 ` Nicolin Chen
2026-05-28 21:59 ` Pranjal Shrivastava
2026-05-27 22:14 ` [PATCH v7 07/11] iommu/arm-smmu-v3: Add CMDQ_PROD_STOP_FLAG to gate CMDQ submissions Pranjal Shrivastava
2026-05-28 19:41 ` Nicolin Chen
2026-05-28 21:57 ` Pranjal Shrivastava
2026-05-27 22:14 ` [PATCH v7 08/11] iommu/arm-smmu-v3: Implement pm_runtime & system sleep ops Pranjal Shrivastava
2026-05-28 19:39 ` Nicolin Chen
2026-05-28 21:21 ` Pranjal Shrivastava
2026-05-28 22:13 ` Nicolin Chen
2026-05-28 23:30 ` Pranjal Shrivastava
2026-05-27 22:14 ` [PATCH v7 09/11] iommu/arm-smmu-v3: Enable pm_runtime and setup devlinks Pranjal Shrivastava
2026-05-28 20:13 ` Nicolin Chen
2026-05-28 21:36 ` Pranjal Shrivastava
2026-05-27 22:14 ` [PATCH v7 10/11] iommu/arm-smmu-v3: Invoke pm_runtime before hw access Pranjal Shrivastava
2026-05-28 20:28 ` Nicolin Chen
2026-05-28 21:46 ` Pranjal Shrivastava
2026-05-28 22:01 ` Nicolin Chen
2026-05-28 22:25 ` Pranjal Shrivastava
2026-05-28 23:18 ` Nicolin Chen
2026-05-29 14:48 ` Pranjal Shrivastava
2026-06-03 22:18 ` Daniel Mentz
2026-06-04 7:18 ` Pranjal Shrivastava
2026-05-27 22:14 ` [PATCH v7 11/11] iommu/arm-smmu-v3: Add KUnit unit tests for Runtime PM Pranjal Shrivastava
2026-05-28 21:43 ` Nicolin Chen
2026-05-28 23:10 ` Pranjal Shrivastava
2026-05-28 23:21 ` Nicolin Chen
2026-05-28 23:33 ` Pranjal Shrivastava
2026-05-28 18:05 ` [PATCH v7 00/11] iommu/arm-smmu-v3: Implement Runtime/System Sleep ops Nicolin Chen
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