On 3/5/19 10:36 PM, Harald Geyer wrote: > Marek Vasut writes: >> On 3/5/19 5:10 PM, Harald Geyer wrote: >>> Marek Vasut writes: >>>> On 3/5/19 11:07 AM, Harald Geyer wrote: >>>>> marek.vasut@xxxxxxxxx writes: >>>>>> From: Marek Vasut <marek.vasut+renesas@xxxxxxxxx> >>>>>> >>>>>> Reword the binding document to make it clear how the propeties work >>>>>> and which properties affect which other properties. >>>>>> >>>>>> Signed-off-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxx> >>>>>> Cc: Harald Geyer <harald@xxxxxxxxx> >>>>>> Cc: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx> >>>>>> Cc: Linus Walleij <linus.walleij@xxxxxxxxxx> >>>>>> Cc: Mark Brown <broonie@xxxxxxxxxx> >>>>>> Cc: Rob Herring <robh@xxxxxxxxxx> >>>>>> Cc: linux-renesas-soc@xxxxxxxxxxxxxxx >>>>>> To: devicetree@xxxxxxxxxxxxxxx >>>>>> --- >>>>>> V2: - Make "gpios" a mandatory property >>>>>> - Reword "gpio-states" property description >>>>>> - Change "enable-gpio" to "enable-gpios" to match modern DT rules >>>>>> Note: The recent gpio-regulator rework caused breakage. While the >>>>>> changes in the gpio-regulator code were according to the DT >>>>>> binding document, they stopped working with older DTs. Make >>>>>> the binding document clearer to prevent such breakage in the >>>>>> future. >>>>> >>>>> Thanks for the update. I think it addresses all my concerns except for >>>>> one: >>>>> >>>>>> +- gpios-states : State of GPIO pins in "gpios" array that is set until >>>>>> + changed by the first consumer. 0: LOW, 1: HIGH. >>>>>> + Default is LOW if nothing else is specified. >>>>> >>>>> I still believe this not true: There is no guarantee that the regulator >>>>> core won't change the state of GPIO pins before the first consumer comes >>>>> up. >>>> >>>> Why would it do that ? >>> >>> Because the regulator core doesn't know about this driver specific >>> property at all. And without any constraints placed by consumers, the >>> core is free to choose any state whatsoever at any point in time. >> >> But git grep seems to disagree, see drivers/regulator/gpio-regulator.c: >> ret = of_property_read_u32_index(np, "gpios-states", i, >> >> The core sets the pins to such a value until the consumer takes over. > > I think we have a misunderstanding of terminology. When I write "regulator > core", I mean the driver independent regulator code. The line you quote > above is part of the gpio-regulator driver and thus not part of what > I call the "regulator core". > > AFAICS the data from the property is only stored in a driver specific > data structure (and not used at all outside of probe) but never passed > to what I call the regulator core. > > Why do you believe there is a guarantee that the value set during > probeing is preserved until a consumer takes over? It is the only sensible behavior and the behavior I see people expect from this property. I presume it solidified in this sort of semi-defined state, so we're stuck with assuming it behaves this way to maintain compatibility. -- Best regards, Marek Vasut
