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

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Date:   Mon, 16 Aug 2021 16:41:46 +0530
From:   Deepak Kumar Singh <deesin@...eaurora.org>
To:     Stephen Boyd <swboyd@...omium.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Sibi Sankar <sibis@...eaurora.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


On 8/11/2021 9:55 AM, Stephen Boyd wrote:
> Quoting Bjorn Andersson (2021-08-10 16:11:10)
>> On Tue 10 Aug 14:18 CDT 2021, Stephen Boyd wrote:
>>
>>> 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.
>> Sounds like in a system without autosleep (or userspace equivalent) it
>> would be desirable to leave the SoC in this lower state than to wake up
>> the system handle the crash and then just idle?
>>
>> But leaving the system in this state will result in you missing your
>> important phone calls...
>>
> Yes I think we should just add a comment to the code and commit text and
> move on.
Thanks, updated in patch set V2