linux-kernel - Re: [PATCH V2 00/13] soc: imx: gpcv2: support i.MX8MM

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Date:   Thu, 22 Jul 2021 08:36:57 +0200
From:   Frieder Schrempf <frieder.schrempf@...tron.de>
To:     Lucas Stach <l.stach@...gutronix.de>,
        "Peng Fan (OSS)" <peng.fan@....nxp.com>, robh+dt@...nel.org,
        shawnguo@...nel.org, s.hauer@...gutronix.de
Cc:     kernel@...gutronix.de, festevam@...il.com, linux-imx@....com,
        p.zabel@...gutronix.de, krzk@...nel.org, agx@...xcpu.org,
        marex@...x.de, andrew.smirnov@...il.com,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, ping.bai@....com, aford173@...il.com,
        abel.vesa@....com, Peng Fan <peng.fan@....com>
Subject: Re: [PATCH V2 00/13] soc: imx: gpcv2: support i.MX8MM

Hi Lucas,

On 21.07.21 22:51, Lucas Stach wrote:
> Hi Frieder,
> 
> Am Donnerstag, dem 20.05.2021 um 17:16 +0200 schrieb Frieder Schrempf:
>> On 19.05.21 18:09, Frieder Schrempf wrote:
>>> On 06.05.21 10:32, Frieder Schrempf wrote:
>>>> On 06.05.21 03:04, Peng Fan (OSS) wrote:
>>>>> From: Peng Fan <peng.fan@....com>
>>>>>
>>>>>
>>>>> V2:
>>>>>  - Add R-b/A-b tag
>>>>>  - Merge V1 patch 13 to V2 patch 6
>>>>>  - Drop V1 patch 15
>>>>>  - Merge V1 patch 16 to V2 patch 5 and add comments in patch 5
>>>>> to explain
>>>>>  details
>>>>>  - Add explaination in patch 8 for "why the resets are not
>>>>> defined"
>>>>>
>>>>> This patchset is a pick up Lucas's gpcv2 work for i.MX8MM and
>>>>> several
>>>>> minor changes from me to make it could work with i.MX BLK-CTL
>>>>> driver.
>>>>>
>>>>> Thanks for Lucas's work and suggestion, Frieder Schrempf for
>>>>> collecting
>>>>> all the patches, Jacky Bai on help debug issues.
>>>>
>>>> I tested this series together with the BLK CTL patches by using
>>>> the GPU and the display stack. Everything looks good to me.
>>>>
>>>> Tested-by: Frieder Schrempf <frieder.schrempf@...tron.de>
>>>
>>> So after some more testing on different hardware I stumbled upon
>>> the problem that USB autosuspend doesn't work properly anymore.
>>>
>>> I have an onboard LTE module that is connected to OTG2 on the
>>> i.MX8MM. When using the mainline TF-A (that enables USB power-
>>> domains by default) and removing the power-domain control from the
>>> kernel, the device comes up after a few seconds and is enumerated
>>> on the bus.
>>>
>>> Now, when I let the kernel control the power-domains, the device
>>> comes up at boot, but isn't enumerated on the USB bus. As soon as I
>>> disable autosuspend for the port, it comes up.
>>>
>>> Is this something that needs to be fixed on the USB driver side or
>>> is something to be considered for the GPCv2 driver?
>>
>> So I think this is something that needs to be covered on the USB
>> driver side. I would expect that a device appearing on the bus should
>> resume the autosuspended bus, but I don't really know much about USB
>> so there might be other things I miss. For now I will disable
>> autosuspend in this case.
>>
>> A different, probably more severe problem is that I was still able to
>> reliably run into lockups with suspend/resume and the GPU. I thought
>> I had tested this before as it was one of the things that already
>> failed with the previous implementation, but I must have missed
>> something as it still fails with kernel v5.12.1 + v2 of the GPC
>> patches.
>>
>> This is how I run into the lockup:
>>
>> echo mem > /sys/power/state  # Sleep
>>                              # Wake up again
>> glmark2-es2-drm              # Use the GPU
>>                              # Device locks up
>>
>> Peng, is this something you can reproduce?
> 
> I could reproduce this issue on my last GPC+BLK_CTRL series. This was
> caused by a bad interaction between our slightly unusual way to control
> the nested power domains via runtime PM and the system suspend/resume
> code, which lead to some of the power domains not properly coming up
> again in the resume path. v2 of my series fixes this issue and the
> above sequence works as expected.

Glad you could reproduce and fix this issue. Thanks for the effort. I will try to do some tests myself soon.

Thanks
Frieder