linux-kernel - Re: [PATCH v4 1/5] soc: qcom: rpmh-rsc: Corrently ignore CPU_CLUSTER

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Date:   Thu, 23 Apr 2020 19:38:52 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Douglas Anderson <dianders@...omium.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        rafael.j.wysocki@...el.com
Cc:     mka@...omium.org, mkshah@...eaurora.org, evgreen@...omium.org,
        Douglas Anderson <dianders@...omium.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/5] soc: qcom: rpmh-rsc: Corrently ignore CPU_CLUSTER_PM notifications

Quoting Douglas Anderson (2020-04-22 14:54:59)
> Our switch statement doesn't have entries for CPU_CLUSTER_PM_ENTER,
> CPU_CLUSTER_PM_ENTER_FAILED, and CPU_CLUSTER_PM_EXIT and doesn't have
> a default.  This means that we'll try to do a flush in those cases but
> we won't necessarily be the last CPU down.  That's not so ideal since
> our (lack of) locking assumes we're on the last CPU.
> 
> Luckily this isn't as big a problem as you'd think since (at least on
> the SoC I tested) we don't get these notifications except on full
> system suspend.  ...and on full system suspend we get them on the last
> CPU down.  That means that the worst problem we hit is flushing twice.
> Still, it's good to make it correct.
> 
> Fixes: 985427f997b6 ("soc: qcom: rpmh: Invoke rpmh_flush() for dirty caches")
> Reported-by: Stephen Boyd <swboyd@...omium.org>
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
> ---

Reviewed-by: Stephen Boyd <swboyd@...omium.org>