Messages in this thread | | | Date | Thu, 25 Jul 2019 12:41:25 +0300 | From | Peter De Schrijver <> | Subject | Re: [PATCH v1] soc/tegra: pmc: Query PCLK clock rate at probe time |
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On Thu, Jul 18, 2019 at 10:45:31AM +0100, Jon Hunter wrote: > > On 08/07/2019 00:08, Dmitry Osipenko wrote: > > The PCLK clock is running off SCLK, which is a critical clock that is > > very unlikely to randomly change its rate. It's also a bit clumsy (and > > apparently incorrect) to query the clock's rate with interrupts being > > disabled because clk_get_rate() takes a mutex and that's the case during > > suspend/cpuidle entering. Lastly, it's better to always fully reprogram > > PMC state because it's not obvious whether it could be changed after SC7. > > I agree with the first part, but I would drop the last sentence because > I see no evidence of this. Maybe Peter can confirm. >
SCLK and PCLK certainly can change rate at runtime, although the changes for this haven't made it upstream yet. It's indeed not very obvious, but certainly doable.
Peter.
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