linux-kernel - Re: [RFT][PATCH v2 1/2] PM / domains: Rework governor code to be more consistent

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Date:   Mon, 6 Nov 2017 15:38:01 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Tero Kristo <t-kristo@...com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Ramesh Thomas <ramesh.thomas@...el.com>,
        Alex Shi <alex.shi@...aro.org>
Subject: Re: [RFT][PATCH v2 1/2] PM / domains: Rework governor code to be more consistent

[...]

>>>
>>> So I guess I'll simply evaluate dev_pm_qos_read_value(dev) if
>>> subsys_data or subsys_data->domain_data is not there.
>>
>> Yes.
>>
>> However, if it returns -1, what value should you pick? 0?
>
> Without the second patch, -1 will just mean "no suspend", so the
> parent cannot be suspended too, but that should just work AFAICS
> (effective_constraint_ns may be -1 too at that point, if present).

I am fine with whatever policy you pick.

However, I suspect it may be more tricky respecting a -1 (no suspend),
because this means dev_update_qos_constraint() then may continue to
return a negative value, which you changed the caller,
default_suspend_ok(), to not cope with.

Anyway, let me look at the code one you posted a new version. :-)

[...]

Kind regards
Uffe