Hello Koen, On Mon, 3 Aug 2009, Koen Kooi wrote: > I'm to trying to lower VDD2 on beagleboard to something slightly below 1V > instead of the current slightly above 1V setting, but I'm having a hard time > figuring out how to do that in the linux-omap (non-PM) tree. > I grepped in (admittedly 2.6.29) arch/arm/mach-omap2 and it only returned hits > that seem to be related to smartreflex. It should be possible to backport sr_voltagescale_vcbypass() from the PM branch smartreflex.c file. Despite the location, there's not much that has to do with SmartReflex. > Now, enabling smartreflex would accomplish my goal if the beagleboards > had there efuses blown, which they didn't and the debug values make some > of my boards lock up :( So the questions I have are: > > o How do I lower VDD2 in the non-PM kernel, should I be doing it in uboot or > in the kernel? > > o For the PM kernel, where should I go patching the VDD2 reference value? You can copy the table you want to modify from mach-omap2/omap3-opp.h into the particular board file, then tinker with the values appropriately. Do you just want to run at VDD2 OPP1? That entry is already in the omap3-opp.h file and is probably <1 Vdc. Just FYI, there are some system devices that are known to not work at this OPP; I think it is either EHCI or MUSB. > And the most important question: > > o Would a patch to lower the default value of VDD2 be accepted into the tree? > Can it be lowered globally or should it be guarded with an > machine_is_omap3beagle() clause? Probably there would be a strong desire to use the OPP levels from the TI Data Manual Operating Condition Addenda, since TI has apparently done some validation on these levels, and let people patch their own custom values in their own trees if they wanted to run at something unusual. - Paul -- 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
