Re: [PATCH] iommu/vt-d: Add RPLS to quirk list to skip TE disabling

[Lu Baolu <baolu.lu@linux.intel.com>]

On 2/25/22 10:12 PM, Vivi, Rodrigo wrote:
> On Fri, 2022-02-25 at 10:20 +0800, Lu Baolu wrote:
>> On 2/24/22 9:39 PM, Vivi, Rodrigo wrote:
>>> On Thu, 2022-02-24 at 13:42 +0800, Lu Baolu wrote:
>>>> On 2/23/22 2:29 PM, Tejas Upadhyay wrote:
>>>>> The VT-d spec requires (10.4.4 Global Command Register, TE
>>>>> field) that:
>>>>>
>>>>> Hardware implementations supporting DMA draining must drain
>>>>> any in-flight DMA read/write requests queued within the
>>>>> Root-Complex before completing the translation enable
>>>>> command and reflecting the status of the command through
>>>>> the TES field in the Global Status register.
>>>>>
>>>>> Unfortunately, some integrated graphic devices fail to do
>>>>> so after some kind of power state transition. As the
>>>>> result, the system might stuck in iommu_disable_translati
>>>>> on(), waiting for the completion of TE transition.
>>>>>
>>>>> This adds RPLS to a quirk list for those devices and skips
>>>>> TE disabling if the qurik hits.
>>>>>
>>>>> Fixes:https://gitlab.freedesktop.org/drm/intel/-/issues/4898
>>>>> Fixes: LCK-10789
>>>> Remove this please.
>>> good catch. Wrong use of Fixes tag.
>>> "Fixes:" should only be used for patches fixing other patches and
>>> mentioning the commit id.
>> This is still a fix patch, right? If so,
>>
>> Fixes: b1012ca8dc4f9 "iommu/vt-d: Skip TE disabling on quirky gfx
>> dedicated iommu"
>> Cc:stable@vger.kernel.org
> hm... you have a point, but I'm not comfortable with this because
> for me it is like an addition of a pci id of a new platform.
> Older kernels won't have the support for that anyway.
> and if for every new platform we add here we need to blame this
> b1012ca8dc4f9 (which did the right time when it was created)
> it doesn't look fair to me.

I have no idea about the graphic roadmap. So I'd like you to decide it.

> 
>>> Baolu,
>>> could you mind if we use
>>>
>>> Closes:https://gitlab.freedesktop.org/drm/intel/-/issues/4898
>>>
>>> or maybe
>>>
>>> References:https://gitlab.freedesktop.org/drm/intel/-/issues/4898
>>>
>>> This last one seems to be the one use in drivers/iommu
>>> and the Closes is what we use in drm-intel, hence the one used
>>> with gitlab.freedesktop links in general.
>> How about "Link:"?
>>
>> As Documentation/process/submitting-patches.rst states:
>>
>> If related discussions or any other background information behind the
>> change
>> can be found on the web, add 'Link:' tags pointing to it. In case
>> your patch
>> fixes a bug, for example, add a tag with a URL referencing the report
>> in the
>> mailing list archives or a bug tracker; if the patch is a result of
>> some
>> earlier mailing list discussion or something documented on the web,
>> point to
>> it.
> yeap, "Link:" works well too.
> 
> With these changes could we get your ack to merge to drm-intel?

This change in VT-d driver looks good to me.

Acked-by: Lu Baolu <baolu.lu@linux.intel.com>

Best regards,
baolu
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