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

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Date:   Thu, 9 Dec 2021 22:44:25 +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 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.