linux-kernel - Re: [PATCH 1/4] iommu/exynos: Set correct dma mask for SysMMU v5+

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Message-ID: <9afb1e98-706f-ed61-892c-e3cc321364b4@linaro.org>
Date:   Sun, 3 Jul 2022 20:50:43 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Sam Protsenko <semen.protsenko@...aro.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Cc:     Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Janghyuck Kim <janghyuck.kim@...sung.com>,
        Cho KyongHo <pullip.cho@...sung.com>,
        Daniel Mentz <danielmentz@...gle.com>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        iommu@...ts.linux-foundation.org, iommu@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] iommu/exynos: Set correct dma mask for SysMMU v5+

On 02/07/2022 23:37, Sam Protsenko wrote:
> SysMMU v5+ supports 36 bit physical address space. Set corresponding DMA
> mask to avoid falling back to SWTLBIO usage in dma_map_single() because
> of failed dma_capable() check.
> 
> The original code for this fix was suggested by Marek.
> 
> Originally-by: Marek Szyprowski <m.szyprowski@...sung.com>

This is some tip specific tag, I don't think checkpatch allows it.
Either use suggesgted-by or co-developed-by + SoB.

> Signed-off-by: Sam Protsenko <semen.protsenko@...aro.org>
> ---
>  drivers/iommu/exynos-iommu.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> index 71f2018e23fe..28f8c8d93aa3 100644
> --- a/drivers/iommu/exynos-iommu.c
> +++ b/drivers/iommu/exynos-iommu.c
> @@ -647,6 +647,14 @@ static int exynos_sysmmu_probe(struct platform_device *pdev)
>  		}
>  	}
>  
> +	if (MMU_MAJ_VER(data->version) >= 5) {
> +		ret = dma_set_mask(dev, DMA_BIT_MASK(36));
> +		if (ret) {
> +			dev_err(dev, "Unable to set DMA mask: %d\n", ret);

Missing cleanup: iommu_device_unregister
and probably also: iommu_device_sysfs_remove

> +			return ret;
> +		}
> +	}
> +
>  	/*
>  	 * use the first registered sysmmu device for performing
>  	 * dma mapping operations on iommu page tables (cpu cache flush)


Best regards,
Krzysztof