From mboxrd@z Thu Jan 1 00:00:00 1970 From: t.figa@samsung.com (Tomasz Figa) Date: Wed, 19 Sep 2012 12:34:31 +0200 Subject: [PATCH v2 1/5] mmc: host: sdhci-s3c: Add broken-voltage DT property for broken voltage quirk In-Reply-To: References: <1346748609-11115-1-git-send-email-t.figa@samsung.com> <1587150.uFGRdL0s8e@amdc1227> Message-ID: <1907099.4JSZthrgh2@amdc1227> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Chris, On Wednesday 19 of September 2012 06:24:46 Chris Ball wrote: > Hi Tomasz, > > On Wed, Sep 19 2012, Tomasz Figa wrote: > > Hi Chris, > > > > On Wednesday 19 of September 2012 01:42:01 Chris Ball wrote: > >> On Tue, Sep 04 2012, Tomasz Figa wrote: > >> > Some boards use fixed voltage regulator for vmmc supply (e.g. for > >> > eMMC > >> > memories). MMC_CAP2_BROKEN_VOLTAGE must be enabled for them to > >> > operate > >> > correctly. > >> > >> Is there a reason we can't make this a property on the regulator > >> instead?> > > Is there a reason we can't make this a property of the mmc subsystem? > > ;) > > > > Now, seriously, could you elaborate on this a bit more? Do you mean > > that a regulator should provide a dummy set voltage operation that > > would accept any voltage? > > Sorry for the terseness. > > It seems like we're encoding exactly the same information twice in two > different subsystems -- I don't see the point, so I'd like to think > about how we could do better. > > For example, if we're only concerned about fixed regulators, could we > just detect a fixed regulator in the driver and avoid the failing call > to regulator_set_voltage() directly, without needing to go via this > capability? Seems like the capability doesn't tell us anything we > couldn't already have known. We could just check if the regulator provides the capability to change the voltage. I don't see any direct way of querying the regulator for provided capabilities (correct me if I'm just blind), but calling regulator_count_voltages() on the regulator and checking if the returned value is 1 should be enough to assume that the regulator is fixed. What do you think? Best regards, -- Tomasz Figa Samsung Poland R&D Center