Messages in this thread | | | From | Ulf Hansson <> | Date | Fri, 3 Sep 2021 10:55:39 +0200 | Subject | Re: [PATCH 3/3] PM: domains: Add a ->dev_get_performance_state() callback to genpd |
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On Fri, 3 Sept 2021 at 08:00, Dmitry Osipenko <digetx@gmail.com> wrote: > > 02.09.2021 13:16, Ulf Hansson пишет: > > Hardware may be preprogrammed to a specific performance state, which may > > not be zero initially during boot. This may lead to that genpd's current > > performance state becomes inconsistent with the state of the hardware. To > > deal with this, the driver for a device that is being attached to its > > genpd, need to request an initial performance state vote, which is > > typically done by calling some of the OPP APIs while probing. > > > > In some cases this would lead to boilerplate code in the drivers. Let's > > make it possible to avoid this, by adding a new optional callback to genpd > > and invoke it per device during the attach process. In this way, the genpd > > provider driver can inform genpd about the initial performance state that > > is needed for the device. > > > > Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> > > --- > > drivers/base/power/domain.c | 8 +++++--- > > include/linux/pm_domain.h | 2 ++ > > 2 files changed, 7 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c > > index 800adf831cae..1a6f3538af8d 100644 > > --- a/drivers/base/power/domain.c > > +++ b/drivers/base/power/domain.c > > @@ -2640,13 +2640,15 @@ static void genpd_dev_pm_sync(struct device *dev) > > genpd_queue_power_off_work(pd); > > } > > > > -static int genpd_get_default_performance_state(struct device *dev, > > +static int genpd_get_default_performance_state(struct generic_pm_domain *genpd, > > + struct device *dev, > > unsigned int index) > > { > > int pstate = of_get_required_opp_performance_state(dev->of_node, index); > > > > if (pstate == -ENODEV || pstate == -EOPNOTSUPP) > > - return 0; > > + pstate = genpd->dev_get_performance_state ? > > + genpd->dev_get_performance_state(genpd, dev) : 0; > > > > return pstate; > > } > > @@ -2701,7 +2703,7 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev, > > } > > > > /* Set the default performance state */ > > - pstate = genpd_get_default_performance_state(dev, index); > > + pstate = genpd_get_default_performance_state(pd, dev, index); > > If base device is suspended, then its performance state is zero. > > When device will be rpm-resumed, then its performance should be set to > the default state. > > You're setting performance state of the wrong device, it should be the > base device and not the virtual domain device.
No I am not. :-) Let me elaborate.
For the single PM domain case, 'dev' and 'base_dev' are pointing to the same device. So this works fine.
For the multiple PM domain case or when attaching goes via genpd_dev_pm_attach_by_id(), 'dev' is the virtual device registered in genpd_dev_pm_attach_by_id(). In this case, it's 'dev' that is becoming attached to genpd and not the 'base_dev'. Note also that, runtime PM has not been enabled for 'dev' yet at this point and 'dev' has been assigned the same OF node as 'base_dev", to allow OF parsing to work as is for it.
Moreover, to deal with runtime PM in the multiple PM domain case, the consumer driver should create a device link. Along the lines of this: device_link_add(base_dev, dev, DL_FLAG_PM_RUNTIME | DL_FLAG_STATELESS), thus assigning the virtual device ('dev') as the supplier for its consumer device ('base_dev').
> > These all is handled properly by my patch [1]. Hence it's complicated > for the reason.
See above. It shouldn't have to be complicated. If it still is, there is something to fix for the multiple PM domain case.
> > [1] > https://patchwork.ozlabs.org/project/linux-tegra/patch/20210831135450.26070-5-digetx@gmail.com/
Kind regards Uffe
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