Re: [PATCH v3 1/2] soc/tegra: pmc: Query PCLK clock rate at probe time

[Peter De Schrijver]

On Tue, Jul 30, 2019 at 08:40:19PM +0300, 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 is possible to get a
> lockup if kernel decides to enter LP2 cpuidle from a clk-notifier, which
> happens occasionally in a case of Tegra30 EMC driver that waits for the
> clk-change event in the clk-notify handler, because CCF's 'prepare' mutex
> in kept locked and thus clk_get_rate() wants to sleep with interrupts
> being disabled.
> 

I don't think this is the right solution. Eventually we will want to
scale sclk and pclk because the clock tree power of those is not
insignificant. Maybe register a notifier which updates the PMC timer
values when pclk changes?

Peter.