linux-kernel - Re: [PATCH v9 05/17] ARM: tegra: Propagate error from tegra_idle_lp2

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Message-ID: <ecb91a99-1e5b-4b76-a27b-56e49e17e9a8@linaro.org>
Date:   Fri, 21 Feb 2020 20:16:00 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        Jasper Korten <jja2000@...il.com>,
        David Heidelberg <david@...t.cz>,
        Peter Geis <pgwipeout@...il.com>, linux-pm@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 05/17] ARM: tegra: Propagate error from
 tegra_idle_lp2_last()

On 21/02/2020 19:42, Dmitry Osipenko wrote:
> 21.02.2020 20:40, Daniel Lezcano пишет:
>> On Fri, Feb 21, 2020 at 08:21:41PM +0300, Dmitry Osipenko wrote:
>>> 21.02.2020 18:16, Daniel Lezcano пишет:
>>>> On Thu, Feb 13, 2020 at 02:51:22AM +0300, Dmitry Osipenko wrote:
>>>>> Technically cpu_suspend() may fail and it's never good to lose information
>>>>> about failure. For example things like cpuidle core could correctly sample
>>>>> idling time in the case of failure.
>>>>>
>>>>> Acked-by: Peter De Schrijver <pdeschrijver@...dia.com>
>>>>> Tested-by: Peter Geis <pgwipeout@...il.com>
>>>>> Tested-by: Jasper Korten <jja2000@...il.com>
>>>>> Tested-by: David Heidelberg <david@...t.cz>
>>>>> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
>>>>> ---
>>>>
>>>> [ ... ]
>>>>
>>>>>  	cpu_cluster_pm_enter();
>>>>>  	suspend_cpu_complex();
>>>>>  
>>>>> -	cpu_suspend(PHYS_OFFSET - PAGE_OFFSET, &tegra_sleep_cpu);
>>>>> +	err = cpu_suspend(PHYS_OFFSET - PAGE_OFFSET, &tegra_sleep_cpu);
>>>>>  
>>>>>  	/*
>>>>>  	 * Resume L2 cache if it wasn't re-enabled early during resume,
>>>>> @@ -208,6 +210,8 @@ void tegra_idle_lp2_last(void)
>>>>>  
>>>>>  	restore_cpu_complex();
>>>>
>>>> If the cpu_suspend fails, does restore_cpu_complex() need to be called ?
>>>
>>> Yes, because suspend_cpu_complex() didn't fail. I don't see any reason
>>> why restore_cpu_complex() shouldn't be called, please clarify yours thought.
>>
>> If the suspend fails, the power down does not happen, thus the logic is not
>> lost and then it not necessary to restore something which has not been lost.
>>
>> I don't know the hardware details, so that may be partially correct.
> 
> At quick glance, the restore_cpu_complex() is only used for restoring
> the GIC's state on Tegra.
> 
> I don't think it's really worth the effort to handle
> restore_cpu_complex() specially in a case of the error condition because
> the chance that the error will ever happen is very small and restoring
> the cluster's state won't cause any trouble in that case.
> 
> Let's keep this patch as-is for simplicity :)

Yep, not a big deal.

Acked-by: Daniel Lezcano <daniel.lezcano@...aro.org>



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