linux-kernel - Re: [PATCH 2/2] remoteproc: core: Prevent sleep when rproc crashes

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Message-ID: <20200407222958.GL20625@builder.lan>
Date:   Tue, 7 Apr 2020 15:29:58 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Siddharth Gupta <sidgup@...eaurora.org>
Cc:     ohad@...ery.com, linux-remoteproc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, tsoni@...eaurora.org,
        psodagud@...eaurora.org, rishabhb@...eaurora.org
Subject: Re: [PATCH 2/2] remoteproc: core: Prevent sleep when rproc crashes

On Wed 19 Feb 18:11 PST 2020, Siddharth Gupta wrote:

> Remoteproc recovery should be fast and any delay will have an impact on the
> user-experience. Use power management APIs (pm_stay_awake and pm_relax) to
> ensure that the system does not go to sleep.
> 
> Signed-off-by: Siddharth Gupta <sidgup@...eaurora.org>
> ---
>  drivers/remoteproc/remoteproc_core.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 5ab65a4..52e318c 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1712,6 +1712,8 @@ static void rproc_crash_handler_work(struct work_struct *work)
>  
>  	if (!rproc->recovery_disabled)
>  		rproc_trigger_recovery(rproc);
> +
> +	pm_relax(&rproc->dev);
>  }
>  
>  /**
> @@ -2242,6 +2244,8 @@ void rproc_report_crash(struct rproc *rproc, enum rproc_crash_type type)
>  		return;
>  	}
>  
> +	pm_stay_awake(&rproc->dev);

Following Mathieu's question I was expecting you to do this on
rproc->dev.parent.

But looking at the implementation of pm_stay_awake(), it ends up being a
nop if dev->power.wakeup isn't specified. This in turn seems to come
from device_wakeup_enable(), which will bail if dev->power.can_wakeup is
not set. But I don't see where this would be set for either the platform
driver or the remoteproc's struct device - and neither one of them have
a "wakeup" attribute in sysfs.

Is there some additional plumbing needed for this?

Regards,
Bjorn

> +
>  	dev_err(&rproc->dev, "crash detected in %s: type %s\n",
>  		rproc->name, rproc_crash_to_string(type));
>  
> -- 
> Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project