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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 v3 1/2] iommu/arm-smmu-v3: Fix CMDQ timeout warning
Date: Wed, 5 Nov 2025 13:22:01 -0800	[thread overview]
Message-ID: <20251105132201.00004a5d@linux.microsoft.com> (raw)
In-Reply-To: <aQupGR8QsS2h7xY/@Asurada-Nvidia>

Hi Nicolin,

On Wed, 5 Nov 2025 11:44:25 -0800
Nicolin Chen <nicolinc@nvidia.com> wrote:

> On Wed, Nov 05, 2025 at 11:06:37AM -0800, Jacob Pan wrote:
> > +	ret = queue_poll(qp);
> > +	if (ret == -ETIMEDOUT) {
> > +		dev_err_ratelimited(smmu->dev, "CMDQ timed out,
> > cons: %08x, prod: 0x%08x\n",
> > +				    llq->cons, llq->prod);
> > +		/* Restart the timer */
> > +		queue_poll_init(smmu, qp);
> > +	} else if (ret) {
> > +		dev_err_ratelimited(smmu->dev, "CMDQ poll error
> > %d\n", ret);  
> 
> I don't think you need this "if (ret)", as queue_poll() returns
> either 0 or -ETIMEOUT. And the patch that I shared with you has
> this noted clearly.
I agree it is not needed for now. But in general it is more robust not
to assume return value never changes.

I can delete that.

Thanks,

Jacob

  reply	other threads:[~2025-11-05 21:22 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-11-05 19:06 [PATCH v3 0/2] SMMU v3 CMDQ fix and improvement Jacob Pan
2025-11-05 19:06 ` [PATCH v3 1/2] iommu/arm-smmu-v3: Fix CMDQ timeout warning Jacob Pan
2025-11-05 19:44   ` Nicolin Chen
2025-11-05 21:22     ` Jacob Pan [this message]
2025-11-05 19:06 ` [PATCH v3 2/2] iommu/arm-smmu-v3: Improve CMDQ lock fairness and efficiency Jacob Pan

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