Re: [PATCH 1/2] remoteproc: qcom: q6v5: Update running state before requesting stop

[Sibi Sankar]

On 2020-06-04 04:03, Evan Green wrote:
> On Tue, Jun 2, 2020 at 10:29 PM Sibi Sankar <sibis@xxxxxxxxxxxxxx> 
> wrote:
> > Evan,
> > Thanks for taking time to review
> > the series.
> >
> > On 2020-06-02 23:14, Evan Green wrote:
> > > On Tue, Jun 2, 2020 at 9:33 AM Sibi Sankar <sibis@xxxxxxxxxxxxxx>
> > > wrote:
> > >>
> > >> Sometimes the stop triggers a watchdog rather than a stop-ack. Update
> > >> the running state to false on requesting stop to skip the watchdog
> > >> instead.
> > >>
> > >> Error Logs:
> > >> $ echo stop > /sys/class/remoteproc/remoteproc0/state
> > >> ipa 1e40000.ipa: received modem stopping event
> > >> remoteproc-modem: watchdog received: sys_m_smsm_mpss.c:291:APPS force
> > >> stop
> > >> qcom-q6v5-mss 4080000.remoteproc-modem: port failed halt
> > >> ipa 1e40000.ipa: received modem offline event
> > >> remoteproc0: stopped remote processor 4080000.remoteproc-modem
> > >>
> > >> Fixes: 3b415c8fb263 ("remoteproc: q6v5: Extract common resource
> > >> handling")
> > >> Cc: stable@xxxxxxxxxxxxxxx
> > >> Signed-off-by: Sibi Sankar <sibis@xxxxxxxxxxxxxx>
> > >> ---
> > >
> > > Are you sure you want to tolerate this behavior from MSS? This is a
> > > graceful shutdown, modem shouldn't have a problem completing the
> > > proper handshake. If they do, isn't that a bug on the modem side?
> >
> > The graceful shutdown is achieved
> > though sysmon (enabled using
> > CONFIG_QCOM_SYSMON). When sysmon is
> > enabled we get a shutdown-ack when we
> > try to stop the modem, post which
> > request stop is a basically a nop.
> > Request stop is done to force stop
> > the modem during failure cases (like
> > rmtfs is not running and so on) and
> > we do want to mask the wdog that we get
> > during this scenario ( The locking
> > already prevents the servicing of the
> > wdog during shutdown, the check just
> > prevents the scheduling of crash handler
> > and err messages associated with it).
> > Also this check was always present and
> > was missed during common q6v5 resource
> > helper migration, hence the unused
> > running state in mss driver.
>
> So you're saying that the intention of the ->running check already in
> q6v5_wdog_interrupt() was to allow either the stop-ack or wdog
> interrupt to complete the stop. This patch just fixes a regression
> introduced during the refactor.
> This patch seems ok to me then. It still sort of seems like a bug that
> the modem responds arbitrarily in one of two ways, even to a "harsh"
> shutdown request.
>
> I wasn't aware of QCOM_SYSMON. Reading it now, It seems like kind of a

TL;DR
Sysmon when enabled adds a lookup
for qmi service 43 (Subsystem
control service). When we shutdown
the modem, we send a SSCTL_SHUTDOWN_REQ
to the service and the modem responds
with a shutdown-ack interrupt. If you
have rmtfs running with -v turned on
you can notice pending efs transactions
being completed followed by a bye I guess.

> lot... do I really need all this? Can I get by with just remoteproc
> stops?
> Anyway, for this patch:
>
> Reviewed-by: Evan Green <evgreen@xxxxxxxxxxxx>

Thanks for the review!

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