Messages in this thread | | | Date | Thu, 18 Jul 2013 13:55:26 +0200 | Subject | Re: [PATCH v3] clk: add MOXA ART SoCs clock driver | From | Jonas Jensen <> |
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On 18 July 2013 13:02, Mark Rutland <mark.rutland@arm.com> wrote: > Ok. I'm just concerned that the linkage isn't explicit or obvious.
> This does leave apb-clock completely dependent on core-clock, and unless > I've missed something there's no linkage between the two described in > the dt.
I can add a description in the core-clock binding and also for apb-clock pointing out that it's set from core-clock.
> How does core-clock physically relate to apb-clock? Does it feed or is > it fed by apb-clock?
apb-clock is entirely a DT construct used by drivers to get the fixed rate 48MHz. It's not fed by core-clock more than what happens in probe.
For UC-7112-LX, drivers using apb-clock are: clocksource, MMC, watchdog
Because clocksource relies on apb-clock, a successful probe of core-clock is critical.
Commonly, drivers look up the apb-clock node and call clk_get_rate.
> Are we always guaranteed to have core-clock if we have apb-clock, and is > it part of the same block in hardware? If so we could describe the > amalgamation as a provider with two clock outputs, with core-clock's > registers for configuration at probe-time.
Yes, as described above, there can not be a apb-clock without core-clock.
I think drivers could find and use core-clock instead. Maybe the abstraction of apb-clock is unnecessary?
Best regards, Jonas
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