linux-kernel - Re: [PATCH v1 2/2] iommu/tegra-smmu: Revert workaround that was needed for Nyan Big Chromebook

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Date:   Sat, 24 Apr 2021 23:41:37 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Guillaume Tucker <guillaume.tucker@...labora.com>,
        Nicolin Chen <nicoleotsuka@...il.com>,
        Thierry Reding <thierry.reding@...il.com>
Cc:     Joerg Roedel <joro@...tes.org>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Krishna Reddy <vdumpa@...dia.com>,
        Will Deacon <will@...nel.org>,
        iommu@...ts.linux-foundation.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 2/2] iommu/tegra-smmu: Revert workaround that was
 needed for Nyan Big Chromebook

24.04.2021 23:27, Dmitry Osipenko пишет:
> 23.04.2021 18:23, Dmitry Osipenko пишет:
>> 23.04.2021 18:01, Guillaume Tucker пишет:
>>> On 02/04/2021 15:40, Dmitry Osipenko wrote:
>>>> 01.04.2021 11:55, Nicolin Chen пишет:
>>>>> On Mon, Mar 29, 2021 at 02:32:56AM +0300, Dmitry Osipenko wrote:
>>>>>> The previous commit fixes problem where display client was attaching too
>>>>>> early to IOMMU during kernel boot in a multi-platform kernel configuration
>>>>>> which enables CONFIG_ARM_DMA_USE_IOMMU=y. The workaround that helped to
>>>>>> defer the IOMMU attachment for Nyan Big Chromebook isn't needed anymore,
>>>>>> revert it.
>>>>>
>>>>> Sorry for the late reply. I have been busy with downstream tasks.
>>>>>
>>>>> I will give them a try by the end of the week. Yet, probably it'd
>>>>> be better to include Guillaume also as he has the Nyan platform.
>>>>>
>>>>
>>>> Indeed, thanks. Although, I'm pretty sure that it's the same issue which
>>>> I reproduced on Nexus 7.
>>>>
>>>> Guillaume, could you please give a test to these patches on Nyan Big?
>>>> There should be no EMEM errors in the kernel log with this patches.
>>>>
>>>> https://patchwork.ozlabs.org/project/linux-tegra/list/?series=236215
>>>
>>> So sorry for the very late reply.  I have tried the patches but
>>> hit some issues on linux-next, it's not reaching a login prompt
>>> with next-20210422.  So I then tried with next-20210419 which
>>> does boot but shows the IOMMU error:
>>>
>>> <6>[    2.995341] tegra-dc 54200000.dc: Adding to iommu group 1
>>> <4>[    3.001070] Failed to attached device 54200000.dc to IOMMU_mapping  
>>>
>>>   https://lava.collabora.co.uk/scheduler/job/3570052#L1120
>>>
>>> The branch I'm using with the patches applied can be found here:
>>>
>>>   https://gitlab.collabora.com/gtucker/linux/-/commits/next-20210419-nyan-big-drm-read/
>>>
>>> Hope this helps, let me know if you need anything else to be
>>> tested.
>>
>>
>> Hello Guillaume,
>>
>> The current linux-next doesn't boot on all ARM (AFAIK), the older
>> next-20210413 works. The above message should be unrelated to the boot
>> problem. It should be okay to ignore that message as it should be
>> harmless in yours case.
>>
> 
> Although, the 20210419 should be good.
> 
> Thierry, do you know what those SOR and Nouveau issues are about?
> 

I don't see DRM driver being loaded at all and no errors related to it
in the log. This means that likely some of the DRM sub-drivers is stuck
in deferred probe.

Guillaume, could you please show contents of
/sys/kernel/debug/devices_deferred ?

These messages also don't look good:

tegra-xusb-padctl 7009f000.padctl: failed to setup XUSB ports: -22
tegra-xusb-padctl: probe of 7009f000.padctl failed with error -22

I don't have T124 and all these problems should be specific to the T124
platform. Somebody with a direct access to hardware should look into it.