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

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Message-ID: <c2c3c37e-0f63-9b89-ed49-78193c46d7bd@linaro.org>
Date:   Mon, 11 Jul 2022 14:27:16 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Sam Protsenko <semen.protsenko@...aro.org>
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        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 08/07/2022 15:18, Sam Protsenko wrote:
> On Sun, 3 Jul 2022 at 21:50, Krzysztof Kozlowski
> <krzysztof.kozlowski@...aro.org> wrote:
>>
>> 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.
>>
> 
> Yes, checkpatch is swearing at that line, though I encountered that
> tag mentioning somewhere in Documentation. Will rework it in v2.

Yes, in tip. It did not go outside of tip.

> 
>>> 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
>>
> 
> Right. Also the correct cleanup should be added for failing
> iommu_device_register() case, above of the quoted code. Will do that
> in v2, thanks.
> 
> Another thing is that "remove" method is missing. But guess I'll get
> to it later, when adding modularization support for this driver.

remove is independent of modules, so it should be here already.

Best regards,
Krzysztof