Messages in this thread | | | Subject | Re: [PATCH v3 04/12] opp: Add dev_pm_opp_sync_regulators() | From | Dmitry Osipenko <> | Date | Mon, 18 Jan 2021 21:35:04 +0300 |
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18.01.2021 11:20, Viresh Kumar пишет: >> +int dev_pm_opp_sync_regulators(struct device *dev) >> +{ >> + struct opp_table *opp_table; >> + struct regulator *reg; >> + int i, ret = 0; >> + >> + /* Device may not have OPP table */ >> + opp_table = _find_opp_table(dev); >> + if (IS_ERR(opp_table)) >> + return 0; >> + >> + /* Regulator may not be required for the device */ >> + if (!opp_table->regulators) >> + goto put_table; >> + >> + mutex_lock(&opp_table->lock); > What exactly do you need this lock for ?
It is needed for protecting simultaneous invocations of dev_pm_opp_sync_regulators() and dev_pm_opp_set_voltage().
The sync_regulators() should be invoked only after completion of the set_voltage() in a case of Tegra power domain driver since potentially both could be running in parallel. For example device driver may be changing performance state in a work thread, while PM domain state is syncing.
But maybe it will be better to move the protection to the PM driver since we're focused on sync_regulators() and set_voltage() here, but there are other OPP API functions which use regulators. I'll need to take a closer look at it.
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