| Message ID | 1498759251-11709-1-git-send-email-sudeep.holla@arm.com |
|---|---|
| State | New |
| Headers | show |
"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>
On 29 June 2017 at 20:00, 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. Right, this makes sense. > > 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> Could we perhaps work out which commit it fixes, or perhaps the problem been there long time ago and we should just add a stable tag? > --- > 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 > One piece is missing to make this fix complete. More precisely, you must also move the call to dev_pm_domain_set(dev, NULL). Currently that is done from genpd_free_dev_data(), as it corresponds to genpd_alloc_dev_data(), but clearly the proper place to call it should be from genpd_remove_device(). Kind regards Uffe
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;
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> --- drivers/base/power/domain.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) -- 2.7.4