Messages in this thread | | | From | Ulf Hansson <> | Date | Fri, 3 Sep 2021 16:09:45 +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 12:06, Dmitry Osipenko <digetx@gmail.com> wrote: > > 03.09.2021 11:55, Ulf Hansson пишет: > > 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 > Are you okay with my variant of handling the suspended device?
Not sure if you intended to post this line?
In any case, I am happy to help and review to move things forward.
> > > >> 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] > Alright, it actually works now on Tegra using the dev in the callback > for the case of multiple domains, I re-checked it. Previously, when I > tried that, there was a conflict in regards to OPP usage, I don't > remember details anymore. Maybe the recent changes that were suggested > by Viresh helped with that. So yes, there is no need to pass the base > device anymore.
Great! So, it seems like $subject patch should be a way forward for you then?
BTW, I forgot to add your Suggested-by: tag for the patch, you certainly deserve at least that. Or perhaps you are fine with co-developed by tag?
Kind regards Uffe
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