linux-kernel - Re: [PATCH] PM / Domains: defer dev_pm_domain_set() until genpd->attach

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Date:   Tue, 11 Jul 2017 11:53:05 -0700
From:   Kevin Hilman <khilman@...libre.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Subject: Re: [PATCH] PM / Domains: defer dev_pm_domain_set() until genpd->attach_dev succeeds if present

"Rafael J. Wysocki" <rafael@...nel.org> writes:

> On Thu, Jun 29, 2017 at 8:00 PM, Sudeep Holla <sudeep.holla@....com> wrote:
>> If the genpd->attach_dev or genpd->power_on fails, genpd_dev_pm_attach
>> may return -EPROBE_DEFER initially. However genpd_alloc_dev_data sets
>> the PM domain for the device unconditionally.
>>
>> When subsequent attempts are made to call genpd_dev_pm_attach, it may
>> return -EEXISTS checking dev->pm_domain without re-attempting to call
>> attach_dev or power_on.
>>
>> platform_drv_probe then attempts to call drv->probe as the return value
>> -EEXIST != -EPROBE_DEFER, which may end up in a situation where the
>> device is accessed without it's power domain switched on.
>>
>> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
>> Cc: Kevin Hilman <khilman@...nel.org>
>> Cc: Ulf Hansson <ulf.hansson@...aro.org>
>> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
>
> Ulf, this looks like a genuine fix to me, any comments?
>

This looks like the right fix to me.

Acked-by: Kevin Hilman <khilman@...libre.com>