linux-kernel - Re: [PATCH V1 1/1] soc: qcom: smp2p: Add wakeup capability to SMP2P IRQ

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Date:   Tue, 10 Aug 2021 12:18:13 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Sibi Sankar <sibis@...eaurora.org>
Cc:     Deepak Kumar Singh <deesin@...eaurora.org>,
        bjorn.andersson@...aro.org, clew@...eaurora.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-remoteproc@...r.kernel.org, Andy Gross <agross@...nel.org>
Subject: Re: [PATCH V1 1/1] soc: qcom: smp2p: Add wakeup capability to SMP2P IRQ

Quoting Sibi Sankar (2021-08-10 10:24:32)
> On 2021-08-09 23:28, Stephen Boyd wrote:
> > Quoting Deepak Kumar Singh (2021-08-09 04:05:08)
> >>
> >> On 8/6/2021 1:10 AM, Stephen Boyd wrote:
> >> > Quoting Deepak Kumar Singh (2021-08-05 09:17:33)
> >> >> Some use cases require SMP2P interrupts to wake up the host
> >> >> from suspend.
> >> > Please elaborate on this point so we understand what sort of scenarios
> >> > want to wakeup from suspend.
> >>
> >> Once such scenario is where WiFi/modem crashes and notifies crash to
> >> local host through smp2p
> >>
> >> if local host is in suspend it should wake up to handle the crash and
> >> reboot the WiFi/modem.
> >
> > Does anything go wrong if the firmware crashes during suspend and the
> > local host doesn't handle it until it wakes for some other reason? I'd
> > like to understand if the crash handling can be delayed/combined with
> > another wakeup.
>
> If the modem firmware crashes
> during suspend, the system comes
> out of xo-shutdown and AFAIK stays
> there until we handle the interrupt.
>

So you're saying we waste power if we don't wakeup the AP and leave the
SoC in a shallow low power state? That would be good to have indicated
in the code via a comment and in the commit text so we know that we want
to handle the wakeup by default.