Re: [PATCH v4 7/7] clk: qcom: add the driver for the MSM8996 APCS clocks

From: Stephen Boyd
Date: Wed Jan 25 2023 - 18:15:50 EST


Quoting Konrad Dybcio (2023-01-25 14:05:27)
>
> On 25.01.2023 22:56, Stephen Boyd wrote:
> >
> > So it is waiting for the CPU clk to be stable? The comment is not clear.
> Okay, so perhaps this is just a misunderstanding because of a lackluster
> comment.. This SYS_APCS_AUX (provided by this driver) is one of the CPU
> clock sources (and probably the "safest" of them all, as it's fed by
> GPLL0 and not the CPU PLLs) the delay is there to ensure it can
> stabilize after setting the divider to DIV2. In a theoretical case, the
> big 8996 cpucc driver could select this clock as a target for one (or
> both) of the per-cluster muxes and it could put the CPUs in a weird state.
>
> As unlikely as that would be, especially considering 8996 (AFAIK) doesn't
> use this clock source coming out of reset / bootloader, this lets us
> ensure one less thing can break.

Great! I look forward to a better comment.