On 2016-09-06 01:21, Tomi Valkeinen wrote: > Hi, > > On 04/09/16 07:26, Stefan Agner wrote: >> The lcd-supply is meant to be optional, there are several device- >> trees not specifying it and the code handles error values silently. >> Therefor, avoid creating a dummy regulator (and the associated >> warning) by using devm_regulator_get_optional. >> >> While at it, document that fact also in the device-tree bindings. > > The binding change looks correct, but using > devm_regulator_get_optional() does not sound correct. > > devm_regulator_get_optional() is to be used when the device in question > truly can function without the power supply. But if the supply is there, > it's just not controlled by the SW, devm_regulator_get() is to be used. The framebuffer device can even function without a display, no problem there.. Probably not really useful... devm_regulator_get creates a dummy regulator and a warning. Afaik, the dummy regulator was meant to be as an aid during development, but not as a permanent solution. This is what the initial commit of the dummy regulator says: > 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. I think we should either make the property mandatory and fix the device trees or we should fix the driver to support an optional regulator. The code already supports the reg_lcd being NULL, which is probably mostly pointless right now as devm_regulator_get always returns a dummy regulator. -- Stefan -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
