Messages in this thread | | | Subject | Re: [PATCH 3/3] PM: domains: Add a ->dev_get_performance_state() callback to genpd | From | Dmitry Osipenko <> | Date | Thu, 9 Sep 2021 16:48:36 +0300 |
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07.09.2021 12:57, Ulf Hansson пишет: > I don't mind extending the genpd API, but it needs to serve a good purpose. > > As I said earlier, genpd doesn't know nor can control how the consumer > driver deploys runtime PM. Unfortunately, that also includes genpd > providers, as the behavior isn't a platform or PM domain specific > thing. This means genpd needs to be generic enough so it works for all > cases. > > In the $subject patch, we rely on the pm_runtime_suspended() check in > dev_pm_genpd_set_performance_state(), which should work for all cases, > even if it may be sub-optimal for some scenarios. > > Note that, in the approach your suggested [1], > pm_runtime_status_suspended() is used instead. This doesn't work when > a consumer driver doesn't enable runtime PM - or calls > pm_runtime_set_active() during ->probe(), because > genpd_runtime_resume() won't be invoked to restore the gpd->rpm_state. > > That said, I wouldn't mind to simply skip adding the > ->dev_get_performance_state() all together, if that is what you > prefer? In this way, it becomes the responsibility for the consumer > driver to do right thing, with the cost of some boilerplate code added > in its ->probe() routine.
Until a day ago, it wasn't clear to me that consumer drivers now can set up rpm_pstate during probe(), which is a cleaner solution that works well. So let's skip adding the questionable ->dev_get_performance_state().
The boilerplate code in the probe() is minimal in comparison to a previous variant with the state-syncing done by rpm-resume callbacks of consumer drivers, it's good enough.
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