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Date: Sat, 13 Feb 2010 15:48:59 +0200 From: Grazvydas Ignotas <notasas@...il.com> To: Mark Brown <broonie@...nsource.wolfsonmicro.com> Cc: Liam Girdwood <lrg@...mlogic.co.uk>, Mike Rapoport <mike@...pulab.co.il>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] regulator: Provide optional dummy regulator for consumers On Sat, Feb 13, 2010 at 1:26 AM, Mark Brown <broonie@...nsource.wolfsonmicro.com> wrote: > On 12 Feb 2010, at 23:01, Grazvydas Ignotas <notasas@...il.com> wrote: > >> On Fri, Feb 12, 2010 at 12:18 PM, Mark Brown >> <broonie@...nsource.wolfsonmicro.com> wrote: >>> >>> In order to ease transitions with drivers are boards start using >>> regulators >>> provide an option to cause all regulator_get() calls to succeed, with a >>> dummy always on regulator being supplied where one has not been >>> configured. >>> A warning is printed whenever the dummy regulator is used to aid system >>> development. >>> >>> This regulator does not implement any regulator operations but will allow >>> simple consumers which only do enable() and disable() calls to run. It >>> is kept separate from the fixed voltage regulator to avoid Kconfig >>> confusion on the part of users when it is extended to allow boards to >>> explicitly use the dummy regulator to simplify cases where the majority >>> of supplies are from fixed regulators without software control. >>> >>> This option is currently only effective for systems which do not specify >>> full constriants. If required an override could also be provided to allow >>> these systems to use the dummy regulator, though it is likely that >>> unconfigured supplies on such systems will lead to error due to >>> regulators being powered down more aggressively when not in use. >>> >>> Signed-off-by: Mark Brown <broonie@...nsource.wolfsonmicro.com> >>> --- >>> >> >> hm, tried intentionally nuking regulator setup on my board to test >> dummy and drivers started failing on regulator_enable() with -1 >> (EPERM?). Looks like dummy doesn't have constraints defined, so not >> much use of this if _enable() is failing anyway. > > Hrmpf. That was working for me - are you running the latest regulator code? > There was a bug where it was requiring CHANGE_STATUS even if the regulator > is always on, which isn't sensible since there is no possibility of actually > changing the status. It should now only be checking for permission to change > status if it would actually do so. There was also a patch yesterday to make > regulators that don't define an is_enabled() report as enabled. Oh, it appears I was missing those patches (they were not in last linux-lest yet), now everything works as expected, thanks. > >> BTW, drivers/mmc/host/omap_hsmmc.c has quite a lot of logic related to >> vcc_aux being available or not (vcc_aux is typically used to power >> some MMC pins and is unused on devices with SD cards, like pandora). I >> wonder if it may cause some functionality change there. > > Yeah, quite possibly. This sort of stuff is one of the reasons it's much > nicer to specify full constraints where possible; it allows drivers that can > have missing supplies to handle that. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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