On Thu, Jul 18, 2013 at 11:36:40AM +0100, Jonas Jensen wrote: > Hi Mark, thanks for taking a look at this. > > On 18 July 2013 11:50, Mark Rutland <[email protected]> wrote: > > This confuses me. moxart_of_clk_init gets called because there was a > > "moxa,moxart-core-clock", node in the dt, but the driver only seems to > > use the information to figure out the configuration of another clock > > ("moxa,moxart-apb-clock"), and never registers a clock specifically for > > the core-clock. > > > > I couldn't find "moxa,moxart-apb-clock" described in mainline. COuld you > > describe the relationship between core-clock and apb-clock? > > It's true core-clock exist only so the register can be mapped.
Ok. I'm just concerned that the linkage isn't explicit or obvious. > > apb-clock is part of a patch set that will add new device tree files for the > MOXA ART SoC, but it's not in mainline: > > http://lists.infradead.org/pipermail/linux-arm-kernel/2013-July/181757.html > > apb-clock could be a fixed rate 48MHz DT only clock, but because we can't > be sure it's 48MHz on all platforms, reading it from a register with > core-clock > is more portable. 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. How does core-clock physically relate to apb-clock? Does it feed or is it fed by apb-clock? 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. Thanks, Mark. > > > 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/
