From: Menon, Nishanth Sent: Thursday, May 27, 2010 9:57 PM To: Premi, Sanjeev Cc: linux-omap@xxxxxxxxxxxxxxx Subject: Re: omap3 pm: dependency between opp layer and cpufreq [snip]--[snip] [sp] Responding via webmail.. so the formatting and quotes are non-standard :( > # OPP support in (OMAP3+ only at the moment) > # XXX The OPP TWL/TPS code should only be included when a TWL/TPS > # PMIC is selected. > ifdef CONFIG_CPU_FREQ > obj-$(CONFIG_ARCH_OMAP3) += opp.o opp_twl_tps.o ok this needs to be split: a) opp_twl_tps should depend on TWL_CORE and not CPUFREQ - there is no need actually b) opp.o should remain dependent on CPU_FREQ. [sp] That was in my next mail. > endif > > But changing CONFIG_CPU_FREQ to CONFIG_TWL4030_POWER leads to these errors: see (b) > [snip--[snip] > > Questions/ comments: > > 1) The linkage between OPP and Voltage are not driven by the PMIC. > They are defined by/for the silicon itself. look carefully at twl -> it is the abstraction where needed for pmic translation of a voltage value - this you agree is PMIC dependent I suppose. > > 2) The implementation for setting the voltage should depend upon the PMIC. ACK- the concept should be independent of PMIC - each PMIC, like 5030/tps Vs custom PMICs have thier own unique mechanisms of setting voltages - the renewed SR series from Thara addresses this concern.(not in pm branch yet - but potentially soon) > > 3) Was there any specific need to tie the functions "opp_get_voltage" and others to cpufreq only? yes, because without cpufreq there is no transitions in the system :) [sp] I does - via bootarg - mpurate! When kernel boots, volatge must be set properly. We cannot rely on u-boot to be settiing everything correctly. e.g. 720MHz on OMAP3530 would fail at nominal 1.2V set by u-boot. > > I am working on a patch that should remove some of these dependencies. > But, trying to open up a discussion as well... do post them. thanks > > Best regards, > Sanjeev > -- > To unsubscribe from this list: send the line "unsubscribe linux-omap" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html Regards, Nishanth Menon -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
