Re: [regression] mhi: ath11k resume fails on some devices

From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: Loic Poulain <loic.poulain@linaro.org>
Cc: Kalle Valo <kvalo@codeaurora.org>,
	ath11k@lists.infradead.org, linux-wireless@vger.kernel.org,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	regressions@lists.linux.dev
Subject: Re: [regression] mhi: ath11k resume fails on some devices
Date: Fri, 24 Sep 2021 15:30:34 +0530	[thread overview]
Message-ID: <20210924100034.GC19050@workstation> (raw)
In-Reply-To: <CAMZdPi8P7YZPhPir+WfS3cY_a7He1m2Pq2uqBhczPdEeoNRb0Q@mail.gmail.com>

On Fri, Sep 24, 2021 at 11:43:55AM +0200, Loic Poulain wrote:
> Hi Kalle,
> 
> On Fri, 24 Sept 2021 at 10:36, Kalle Valo <kvalo@codeaurora.org> wrote:
> >
> > Loic Poulain <loic.poulain@linaro.org> writes:
> >
> > > Hi Kalle,
> > >
> > > On Thu, 16 Sept 2021 at 10:00, Kalle Valo <kvalo@codeaurora.org> wrote:
> > >>
> > >> Hi Loic and Mani,
> > >>
> > >> I hate to be the bearer of bad news again :)
> > >>
> > >> I noticed already a while ago that commit 020d3b26c07a ("bus: mhi: Early
> > >> MHI resume failure in non M3 state"), introduced in v5.13-rc1, broke
> > >> ath11k resume on my NUC x86 testbox using QCA6390. Interestingly enough
> > >> Dell XPS 13 9310 laptop (with QCA6390 as well) does not have this
> > >> problem, I only see the problem on the NUC. I do not know what's causing
> > >> this difference.
> > >
> > > I suppose the NUC is current PCI-Express power during suspend while
> > > the laptop maintains PCIe/M2 power.
> >
> > Sorry, I'm not able to parse that sentence. Can you elaborate more?
> 
> Ouch, yes, I wanted to say that the NUC does not maintain the power of
> PCI express during suspend (leading to PCI D3cold state), whereas the
> laptop maintains the power of the M2 card... well, not sure now I see
> your logs.
> 
> >
> > >> 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.
> 

It will... But we should first try to see what is causing the device to
be in MHI RESET state. We can't add a force resume case without knowing
the rootcause.

And for workaround, we can proceed resume if device is in RESET state
adding a comment on why. But let's first get the MHI debug logs.

> Regards,
> Loic