On Wed, Mar 09, 2022 at 09:55:40PM +0000, Mark Brown wrote:
> On Wed, Mar 09, 2022 at 08:16:07PM +0000, John Keeping wrote:
> > On Wed, Mar 09, 2022 at 04:28:30PM +0000, Mark Brown wrote:
>
> > > I think the device tree binding needs to be clarified here to be
> > > explicit about this since there's obviously some room for user confusion
> > > here. We can probably get away with a change at this point since it's
> > > not hit a release but we do need to try to avoid the situation where any
> > > other implementations use active high polarity for the bindings.
>
> > Taking a quick survey of the other devices that have a pdn-gpios
> > property:
>
> > - tvp5150 is correct with the driver setting 0 to make the device active
>
> > - tas571x also sets 0 to make the device active
>
> > - ak4375 uses the opposite sense setting PDN = 1 to make the device
> > active; this has no in-tree users and was merged as part of v5.17-rc1
> > so it's not in a released kernel yet
>
> Sure, I still think it would be good to update the binding document to
> clarify things as part of your patch - the binding currently just has it
> as the "pdn" pin not the /pdn pin or anything.
I've been thinking about this but I can't really think what to say.
tas571x's binding says:
GPIO specifier for the TAS571x's active low powerdown line
Is that the sort of wording you have in mind?
To me it seems like a general principle that the GPIO_ACTIVE_{HIGH,LOW}
flags should be used to indicate how the pin works so that the driver
consistently uses logical levels regardless of how the hardware is
wired.
