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

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Message-ID: <20211209200141.GA35858@Asurada-Nvidia>
Date:   Thu, 9 Dec 2021 12:01:41 -0800
From:   Nicolin Chen <nicolinc@...dia.com>
To:     Dmitry Osipenko <digetx@...il.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

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?