Re: [PATCH v11 09/16] iommu/arm-smmu-v3: Restore MSI config on resume

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] arm-smmu-v3: Meaningful code and commit message mismatch for ARM_SMMU_FEAT_MSI
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commit 1bda20db5a1330cc7b28d06643bb07428e7318f4
Author: Pranjal Shrivastava <praan@google.com>

iommu/arm-smmu-v3: Restore MSI config on resume

The SMMU's MSI configuration registers (*_IRQ_CFGn) containing target
address, data and memory attributes lose their state when the SMMU is
powered down. This commit introduces arm_smmu_resume_msis() to zero the
registers and restore cached MSI messages. It also states it clears
ARM_SMMU_FEAT_MSI on setup failure to prevent spurious resume attempts.

> In addition, clear ARM_SMMU_FEAT_MSI if MSI setup fails and the driver
> falls back to wired IRQs, preventing spurious MSI resume attempts.

[Severity: Medium]
The commit message mentions clearing ARM_SMMU_FEAT_MSI on MSI setup failure,
but the code to do this appears to be missing from the patch.

Looking at arm_smmu_setup_msis(), the flag is left set when falling back to
wired IRQs:

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:arm_smmu_setup_msis() {
    ...
	if (!dev->msi.domain) {
		dev_info(smmu->dev, "msi_domain absent - falling back to wired irqs\n");
		return;
	}
    ...
	ret = platform_device_msi_init_and_alloc_irqs(dev, nvec, arm_smmu_write_msi_msg);
	if (ret) {
		dev_warn(dev, "failed to allocate MSIs - falling back to wired irqs\n");
		return;
	}
    ...
}

Was the code to clear ARM_SMMU_FEAT_MSI accidentally dropped from this patch?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260929034510.2023173-1-praan@google.com?part=9