linux-kernel - Re: [PATCH v8 6/6] iommu/tegra-smmu: Add pagetable mappings to debugfs

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Message-ID: <8baa58f4-fd3c-1273-d770-035a2fb76c96@gmail.com>
Date:   Thu, 9 Dec 2021 23:03:00 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Nicolin Chen <nicolinc@...dia.com>
Cc:     thierry.reding@...il.com, joro@...tes.org, will@...nel.org,
        vdumpa@...dia.com, jonathanh@...dia.com,
        linux-tegra@...r.kernel.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 6/6] iommu/tegra-smmu: Add pagetable mappings to
 debugfs

09.12.2021 23:01, Nicolin Chen пишет:
> On Thu, Dec 09, 2021 at 10:58:32PM +0300, Dmitry Osipenko wrote:
>> External email: Use caution opening links or attachments
>>
>>
>> 09.12.2021 22:54, Nicolin Chen пишет:
>>> On Thu, Dec 09, 2021 at 10:44:25PM +0300, Dmitry Osipenko wrote:
>>>> External email: Use caution opening links or attachments
>>>>
>>>>
>>>> 09.12.2021 22:24, Nicolin Chen пишет:
>>>>> On Thu, Dec 09, 2021 at 05:49:09PM +0300, Dmitry Osipenko wrote:
>>>>>> External email: Use caution opening links or attachments
>>>>>>
>>>>>>
>>>>>> 09.12.2021 10:38, Nicolin Chen пишет:
>>>>>>> +static unsigned long pd_pt_index_iova(unsigned int pd_index, unsigned int pt_index)
>>>>>>> +{
>>>>>>> +     return (pd_index & (SMMU_NUM_PDE - 1)) << SMMU_PDE_SHIFT |
>>>>>>> +            (pt_index & (SMMU_NUM_PTE - 1)) << SMMU_PTE_SHIFT;
>>>>>>> +}
>>>>>>
>>>>>> I'd change the return type to u32 here, for consistency.
>>>>>
>>>>> The whole file defines iova using "unsigned long", which I see
>>>>> as the consistency... If we change it to u32, it'd be probably
>>>>> necessary to change all iova types to u32 too... So I'd rather
>>>>> keep it "unsigned long" here. If you see a big necessity to do
>>>>> that, an additional patch would be nicer IMHO.
>>>>>
>>>>
>>>> In general IOVA is "unsigned long", of course. But in case of Tegra
>>>> SMMU, we know that is always u32.
>>>>
>>>> Alright, I see now that there are other places in the driver code that
>>>> use "unsigned long", so need to change it in this patch.
>>>
>>> I think we should do that in a separate patch that changes the iova
>>> type in the entire tegra-smmu file. I can add one in this series, if
>>> this makes you happy...
>>>
>>
>> Please keep it "unsigned long", no need for extra patches.
> 
> Oh, I guess that "so need to change it in this patch" should be
> "so (no) need to change it in this patch" then?
> 

Indeed, I missed that typo, sorry.