Hi Lukasz, On Tue, Dec 17, 2013 at 1:44 PM, Lukasz Majewski <l.majewski@xxxxxxxxxxx> wrote: > Hi Jassi, > >> On Tue, Dec 10, 2013 at 10:02 PM, Lukasz Majewski >> <l.majewski@xxxxxxxxxxx> wrote: >> >> >> >> Actually these values are not for PLL, but for the dividers. >> >> If you see below, the PLL rate setting is done through >> >> clk_set_rate() going via CCF. But I found an issue if the divider >> >> values are set via clk_set_rate API. >> >> What I found is, the system goes into freeze if all the divider >> >> values are not set in one shot. So we cannot call multiple >> >> clk_set_rate()'s on each divider. Thats why I continued with >> >> non-CCF way of setting the divider. >> > >> > I see. I'm not an expert on common clock framework (CCF), but for me >> > conceptually clock dividers setting shall be handled by CCF. >> > >> > However, I've poked a bit at CCF. There isn't any out of the box >> > solutions available. >> > >> > A "virtual" clock can be defined and inside its implementation we >> > can atomically set dividers. Another solution would be to hack the >> > current CCF to provide atomic clock operations >> > >> CCF isn't only for clocks that have single divider or gate control >> register. One could define a clock that manipulates more than one >> divider/gate in one CCF callback. It is already abstract enough. So >> implementing a virtual clock is the solution, imho. > > Thanks for sharing your experience. > >> BTW, on my platform linux needs to send a 'non-atomic' IPC message to >> a master co-processor to scale up/down cpufreq. I just define a >> virtual clock and use the generic bL cpufreq driver >> drivers/cpufreq/arm_big_little.c > > My use case is simpler - cpufreq-cpu0.c or arm_bit_little.c (for bL) > driver with maybe two virtual clocks to handle divider's update. > Is it very simple where 5 different dividers with different divider ratios have to be set in one shot. Our clk_set_rate() API as such takes only one freq rate argument. How do you think to combine say 5 divider rates? Regards Arun -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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