On 18 July 2013 13:02, Mark Rutland <[email protected]> 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
