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Re: [PATCH] PM / Domains: defer dev_pm_domain_set() until genpd->attach_dev succeeds if present

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  Re: [PATCH] PM / Domains: defer dev_pm_domain_set() until  genpd->attach_dev succeeds if present "Rafael J. Wysocki" <rafael@kernel.org> - 2017-07-04 22:40 +0200
    Re: [PATCH] PM / Domains: defer dev_pm_domain_set() until genpd->attach_dev succeeds if present Kevin Hilman <khilman@baylibre.com> - 2017-07-11 21:00 +0200

#1681177 — Re: [PATCH] PM / Domains: defer dev_pm_domain_set() until genpd->attach_dev succeeds if present

On Thu, Jun 29, 2017 at 8:00 PM, Sudeep Holla <sudeep.holla@arm.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@rjwysocki.net>
> Cc: Kevin Hilman <khilman@kernel.org>
> Cc: Ulf Hansson <ulf.hansson@linaro.org>
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

Ulf, this looks like a genuine fix to me, any comments?

> ---
>  drivers/base/power/domain.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index da49a8383dc3..b195d34de888 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -1168,8 +1168,6 @@ static struct generic_pm_domain_data *genpd_alloc_dev_data(struct device *dev,
>
>         spin_unlock_irq(&dev->power.lock);
>
> -       dev_pm_domain_set(dev, &genpd->domain);
> -
>         return gpd_data;
>
>   err_free:
> @@ -1221,6 +1219,8 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
>         if (ret)
>                 goto out;
>
> +       dev_pm_domain_set(dev, &genpd->domain);
> +
>         genpd->device_count++;
>         genpd->max_off_time_changed = true;
>
> --
> 2.7.4
>

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#1685296 — Re: [PATCH] PM / Domains: defer dev_pm_domain_set() until genpd->attach_dev succeeds if present

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

> On Thu, Jun 29, 2017 at 8:00 PM, Sudeep Holla <sudeep.holla@arm.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@rjwysocki.net>
>> Cc: Kevin Hilman <khilman@kernel.org>
>> Cc: Ulf Hansson <ulf.hansson@linaro.org>
>> Signed-off-by: Sudeep Holla <sudeep.holla@arm.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@baylibre.com>

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