[regression] mhi: ath11k resume fails on some devices

[Kalle Valo]

Kalle Valo <kvalo at codeaurora.org> writes:

> (adding the new mhi list, yay)
>
> Hi Loic,
>
> Loic Poulain <loic.poulain at linaro.org> writes:
>
>>> Loic Poulain <loic.poulain at linaro.org> writes:
>>>
>>> > On Thu, 16 Sept 2021 at 10:00, Kalle Valo <kvalo at codeaurora.org> wrote:
>>>
>>> >> At the moment I'm running my tests with commit 020d3b26c07a reverted and
>>> >> everything works without problems. Is there a simple way to fix this? Or
>>> >> maybe we should just revert the commit? Commit log and kernel logs from
>>> >> a failing case below.
>>> >
>>> > Do you have log of success case?
>>>
>>> A log from a successful case in the end of email, using v5.15-rc1 plus
>>> revert of commit 020d3b26c07abe27.
>>>
>>> > To me, the device loses power, that is why MHI resuming is failing.
>>> > Normally the device should be properly recovered/reinitialized. Before
>>> > that patch the power loss was simply not detected (or handled at
>>> > higher stack level).
>>>
>>> Currently in ath11k we always keep the firmware running when in suspend,
>>> this is a workaround due to problems between mac80211 and MHI stack.
>>> IIRC the problem was something related MHI creating struct device during
>>> resume or something like that.
>>
>> Could you give a try with the attached patch? It should solve your
>> issue without breaking modem support.
>
> Sorry for taking so long, but I now tested your patch on top of
> v5.15-rc3 and, as expected, everything works as before with QCA6390 on
> NUC x86 testbox.
>
> Tested-by: Kalle Valo <kvalo at codeaurora.org>

I doubt we will find enough time to fully debug this mhi issue anytime
soon. Can we commit Loic's patch so that this regression is resolved?

At the moment I'm doing all my regression testing with commit
020d3b26c07abe27 reverted. That's a risk, I would prefer to do my
testing without any hacks.

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