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Date: Thu, 06 Jun 2013 09:53:41 -0600 From: Stephen Warren <swarren@...dotorg.org> To: "J, KEERTHY" <j-keerthy@...com> CC: "gg@...mlogic.co.uk" <gg@...mlogic.co.uk>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>, "devicetree-discuss@...ts.ozlabs.org" <devicetree-discuss@...ts.ozlabs.org>, "broonie@...nsource.wolfsonmicro.com" <broonie@...nsource.wolfsonmicro.com>, "rob.herring@...xeda.com" <rob.herring@...xeda.com>, "rob@...dley.net" <rob@...dley.net>, "sameo@...ux.intel.com" <sameo@...ux.intel.com>, "wim@...ana.be" <wim@...ana.be>, "lgirdwood@...il.com" <lgirdwood@...il.com>, "Kristo, Tero" <t-kristo@...com>, "lee.jones@...aro.org" <lee.jones@...aro.org>, Ian Lartey <ian@...mlogic.co.uk> Subject: Re: [PATCH v2] mfd: DT bindings for the palmas family MFD On 06/05/2013 09:34 PM, J, KEERTHY wrote: > Hi Stephen, > > Thanks for the quick review. > > Stephen Warren wrote at Wednesday, June 05, 2013 10:44 PM: >> On 06/04/2013 02:41 AM, J Keerthy wrote: >>> From: Graeme Gregory <gg@...mlogic.co.uk> >>> >>> Add the various binding files for the palmas family of chips. There is >>> a top level MFD binding then a seperate binding for regulators IP >> blocks on chips. ... >> Oh, one question though: How does the regulator driver determine the >> register address of the regulator sub-device within the overall PMIC? >> Presumably if these are pluggable independent modules, that could >> change depending on which overall chip the PMIC device is plugged into. >> don't you need a reg property to specify that? > > The variants have identical register addresses. These are not pluggable > Independent modules. All the variants come with all the regulators > Listed above in general. The driver today has a statically defined > Array of all the above mentioned regulators with their addresses. > > drivers/regulator/palmas-regulator.c > > Line 38. I meant the I2C address used to communicate with the regulator registers really, and I suppose the base address of the regulator register block. In the driver, I see this is handled by the top-level Palmas driver creating a regmap object which the regulator driver used. This keeps the regulator driver completely unaware of these issues, only the top-level chip driver cares about this, which is fine. While that justification is in terms of OS-specific code, the basic argument can be applied to the HW itself (the top-level chip implies the I2C address and any register offset), so this really is a HW-driven argument, so I guess it's fine not having a reg property in the top-level regulator node. One question though: I wonder why if the HW IP blocks aren't completely independent modules that can be mixed/matched together to form new chips, there's even a need for a separate regulator node with its own compatible value. Still, I suppose it's a valid way to construct the DT either way, so it's fine. -- 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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