linux-kernel - Re: [PATCH v3 1/2] iommu/arm-smmu-v3: Fix CMDQ timeout warning

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Message-ID: <aQupGR8QsS2h7xY/@Asurada-Nvidia>
Date: Wed, 5 Nov 2025 11:44:25 -0800
From: Nicolin Chen <nicolinc@...dia.com>
To: Jacob Pan <jacob.pan@...ux.microsoft.com>
CC: <linux-kernel@...r.kernel.org>, "iommu@...ts.linux.dev"
	<iommu@...ts.linux.dev>, Will Deacon <will@...nel.org>, Joerg Roedel
	<joro@...tes.org>, Mostafa Saleh <smostafa@...gle.com>, Jason Gunthorpe
	<jgg@...dia.com>, Robin Murphy <robin.murphy@....com>, Zhang Yu
	<zhangyu1@...ux.microsoft.com>, Jean Philippe-Brucker
	<jean-philippe@...aro.org>, Alexander Grest <Alexander.Grest@...rosoft.com>
Subject: Re: [PATCH v3 1/2] iommu/arm-smmu-v3: Fix CMDQ timeout warning

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.

The other caller arm_smmu_cmdq_poll_until_sync() treats the ret
simply as -ETIMEOUT as well. So, let's just keep it in this way.

Nicolin