linux-kernel - Re: [PATCH RESEND v2 4/5] iommu/tegra-smmu: Rework tegra_smmu_probe

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Message-ID: <20210218103510.GA13060@Asurada-Nvidia>
Date:   Thu, 18 Feb 2021 02:35:11 -0800
From:   Nicolin Chen <nicoleotsuka@...il.com>
To:     Guillaume Tucker <guillaume.tucker@...labora.com>
Cc:     will@...nel.org, linux-kernel@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-tegra@...r.kernel.org,
        jonathanh@...dia.com, vdumpa@...dia.com, thierry.reding@...il.com,
        joro@...tes.org, kernel@...labora.com,
        Dmitry Osipenko <digetx@...il.com>,
        "kernelci-results@...ups.io" <kernelci-results@...ups.io>
Subject: Re: [PATCH RESEND v2 4/5] iommu/tegra-smmu: Rework
 tegra_smmu_probe_device()

Hi Guillaume,

Thank you for the test results! And sorry for my belated reply.

On Thu, Feb 11, 2021 at 03:50:05PM +0000, Guillaume Tucker wrote:
> > On Sat, Feb 06, 2021 at 01:40:13PM +0000, Guillaume Tucker wrote:
> >>> It'd be nicer if I can get both logs of the vanilla kernel (failing)
> >>> and the commit-reverted version (passing), each applying this patch.
> >>
> >> Sure, I've run 3 jobs:
> >>
> >> * v5.11-rc6 as a reference, to see the original issue:
> >>   https://lava.collabora.co.uk/scheduler/job/3187848
> >>
> >> * + your debug patch:
> >>   https://lava.collabora.co.uk/scheduler/job/3187849
> >>
> >> * + the "breaking" commit reverted, passing the tests:
> >>   https://lava.collabora.co.uk/scheduler/job/3187851
> > 
> > Thanks for the help!
> > 
> > I am able to figure out what's probably wrong, yet not so sure
> > about the best solution at this point.
> > 
> > Would it be possible for you to run one more time with another
> > debugging patch? I'd like to see the same logs as previous:
> > 1. Vanilla kernel + debug patch
> > 2. Vanilla kernel + Reverted + debug patch
> 
> As it turns out, next-20210210 is passing all the tests again so
> it looks like this got fixed in the meantime:
> 
>   https://lava.collabora.co.uk/scheduler/job/3210192

I checked this passing log, however, found that the regression is
still there though test passed, as the prints below aren't normal:
  tegra-mc 70019000.memory-controller: display0a: read @0xfe056b40:
	 EMEM address decode error (SMMU translation error [--S])
  tegra-mc 70019000.memory-controller: display0a: read @0xfe056b40:
	 Page fault (SMMU translation error [--S])

I was trying to think of a simpler solution than a revert. However,
given the fact that the callback sequence could change -- guessing
likely a recent change in iommu core, I feel it safer to revert my
previous change, not necessarily being a complete revert though.

I attached my partial reverting change in this email. Would it be
possible for you to run one more test for me to confirm it? It'd
keep the tests passing while eliminating all error prints above.

If the fix works, I'll re-send it to mail list by adding a commit
message.

Thanks!
Nicolin

View attachment "0001-iommu-tegra-smmu-Fix-mc-errors-on-tegra124-nyan.patch" of type "text/x-diff" (3127 bytes)