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From: Jacob Pan <jacob.pan@linux.microsoft.com>
To: Nicolin Chen <nicolinc@nvidia.com>
Cc: <linux-kernel@vger.kernel.org>,
	"iommu@lists.linux.dev" <iommu@lists.linux.dev>,
	Will Deacon <will@kernel.org>, Joerg Roedel <joro@8bytes.org>,
	Mostafa Saleh <smostafa@google.com>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Zhang Yu <zhangyu1@linux.microsoft.com>,
	Jean Philippe-Brucker <jean-philippe@linaro.org>,
	Alexander Grest <Alexander.Grest@microsoft.com>
Subject: Re: [PATCH v2 1/2] iommu/arm-smmu-v3: Fix CMDQ timeout warning
Date: Tue, 4 Nov 2025 11:37:28 -0800	[thread overview]
Message-ID: <20251104113728.0000568e@linux.microsoft.com> (raw)
In-Reply-To: <aQpKf2IPD5xeBu1K@Asurada-Nvidia>

Hi Nicolin,

On Tue, 4 Nov 2025 10:48:31 -0800
Nicolin Chen <nicolinc@nvidia.com> wrote:

> On Tue, Nov 04, 2025 at 10:25:39AM -0800, Jacob Pan wrote:
> > > -----------------------------------------------------------------
> > > 
> > > And the commit message should point out:
> > > 
> > > The existing arm_smmu_cmdq_poll_until_not_full() doesn't fit
> > > efficiently nor ideally to the only caller
> > > arm_smmu_cmdq_issue_cmdlist():
> > >  - It uses a new timer at every single call, which fails to limit
> > > to the preset ARM_SMMU_POLL_TIMEOUT_US per issue.  
> 
> > Not following what you mean.
> > The original code below does honor the timeout of
> > ARM_SMMU_POLL_TIMEOUT_US  
> 
> It sets the timeout per arm_smmu_cmdq_poll_until_not_full(), not
> the entire wait-for-space routine. And that's why you moved the
> queue_poll_init() to the caller, right?
> 
Got you! will do.

Thanks,

Jacob


  reply	other threads:[~2025-11-04 19:37 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-10-20 22:43 [PATCH v2 0/2] SMMU v3 CMDQ fix and improvement Jacob Pan
2025-10-20 22:43 ` [PATCH v2 1/2] iommu/arm-smmu-v3: Fix CMDQ timeout warning Jacob Pan
2025-10-30 22:41   ` Nicolin Chen
2025-11-03 23:16     ` Jacob Pan
2025-11-04  1:23       ` Nicolin Chen
2025-11-04 18:25         ` Jacob Pan
2025-11-04 18:48           ` Nicolin Chen
2025-11-04 19:37             ` Jacob Pan [this message]
2025-10-20 22:43 ` [PATCH v2 2/2] iommu/arm-smmu-v3: Improve CMDQ lock fairness and efficiency Jacob Pan
2025-10-31  2:00   ` Nicolin Chen
2025-11-04  1:08     ` Jacob Pan
2025-10-30 15:42 ` [PATCH v2 0/2] SMMU v3 CMDQ fix and improvement Jacob Pan

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