Re: [PATCH v3 3/5] dt-bindings: input: Add poll-interval property

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Fri, Oct 11, 2019 at 10:03:25AM +0200, Michal Vokáč wrote:
> On 10. 10. 19 22:01, Dmitry Torokhov wrote:
> > On Thu, Oct 10, 2019 at 02:40:36PM -0500, Rob Herring wrote:
> > > On Thu, Oct 03, 2019 at 08:12:54AM +0200, Michal Vokáč wrote:
> > > > Add an option to periodicaly poll the device to get state of the inputs
> > > > as the interrupt line may not be used on some platforms.
> > > > 
> > > > Signed-off-by: Michal Vokáč <michal.vokac@ysoft.com>
> > > > ---
> > > > Changes since v2:
> > > >   - None
> > > > 
> > > > Changes since v1:
> > > >   - Use poll-interval instead of linux,poll-interval.
> > > >   - Place the poll-interval binding into the common schema.
> > > >   - Properly describe that either interrupts or poll-interval property is
> > > >     required.
> > > >   - Fix the example to pass validation.
> > > > 
> > > >   .../bindings/input/fsl,mpr121-touchkey.yaml        | 25 +++++++++++++++++++++-
> > > >   Documentation/devicetree/bindings/input/input.yaml |  4 ++++
> > > >   2 files changed, 28 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/Documentation/devicetree/bindings/input/fsl,mpr121-touchkey.yaml b/Documentation/devicetree/bindings/input/fsl,mpr121-touchkey.yaml
> > > > index c6fbcdf78556..035b2fee4491 100644
> > > > --- a/Documentation/devicetree/bindings/input/fsl,mpr121-touchkey.yaml
> > > > +++ b/Documentation/devicetree/bindings/input/fsl,mpr121-touchkey.yaml
> > > > @@ -17,6 +17,10 @@ description: |
> > > >   allOf:
> > > >     - $ref: input.yaml#
> > > > +oneOf:
> > > 
> > > It should be valid to have both properties present, right?
> > 
> > The poll does not really sense and does not have any effect when
> > interrupt is supplied.
> 
> From technical point of view, yes it is possible to have both
> properties. But I agree that it does not really make sense to
> use both at the same time.
> 
> > > The h/w description can't know what the OS supports.
> > 
> > It also has no idea what OS does at all and whether it even pays
> > attention to any of these properties. We are just trying to say here "I
> > do not have an interrupt wired, so for this device's primary use case
> > (that is coupled with a certain $PRIMARY OS) we need to poll the
> > controller ever so often to handle our use case".
> 
> If I understand correctly the relationship between Linux and DT
> binding, in Linux we are free to implement just part of all the
> possible configuration options described by the binding.
> 
> In this case if somebody would enable both interrupt and polling,
> we will happily use the interrupt mode only. Maybe it would be nice
> to at least print a message that the poll-intervall is ignored?
> 
> > > In that case, we should use 'anyOf' here instead.
> 
> What I am afraid of is that some DT writers may really use both
> properties and expect that Linux will actually do something useful
> in this case. Anyway, I am OK with that.

OK, I changed it to "anyOf", folded into driver change and applied.

-- 
Dmitry