linux-kernel - Re: [PATCH 10/10] dt-bindings: rtc: pcf2127: add PCF2131 INT_A and INT

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Date:   Fri, 11 Feb 2022 20:16:27 +0000
From:   Hugo Villeneuve <hvilleneuve@...onoff.com>
To:     "hugo@...ovil.com" <hugo@...ovil.com>,
        "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>
CC:     "robh@...nel.org" <robh@...nel.org>,
        "a.zummo@...ertech.it" <a.zummo@...ertech.it>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 10/10] dt-bindings: rtc: pcf2127: add PCF2131 INT_A and
 INT_B support

On Thu, 2022-02-10 at 17:55 -0500, Hugo Villeneuve wrote:
> On Thu, 10 Feb 2022 23:32:32 +0100
> Alexandre Belloni <alexandre.belloni@...tlin.com> wrote:
> 
> > On 10/02/2022 17:12:34-0500, Hugo Villeneuve wrote:
> > > On Tue, 8 Feb 2022 21:20:28 -0600
> > > Rob Herring <robh@...nel.org> wrote:
> > > 
> > > > On Tue, Jan 25, 2022 at 03:00:09PM -0500, Hugo Villeneuve
> > > > wrote:
> > > > > From: Hugo Villeneuve <hvilleneuve@...onoff.com>
> > > > > 
> > > > > The PCF2131 has two output interrupt pins, named INT_A and
> > > > > INT_B.
> > > > > 
> > > > > Add properties to identify onto which pin we want the alarm
> > > > > interrupt
> > > > > to be routed. It can be either one, or both.
> > > > > 
> > > > > These properties are automatically set to false for variants
> > > > > other
> > > > > than PCF2131 (ex: PCF2127).
> > > > > 
> > > > > Signed-off-by: Hugo Villeneuve <hvilleneuve@...onoff.com>
> > > > > ---
> > > > >  .../devicetree/bindings/rtc/nxp,pcf2127.yaml  | 23
> > > > > +++++++++++++++++++
> > > > >  1 file changed, 23 insertions(+)
> > > > > 
> > > > > diff --git
> > > > > a/Documentation/devicetree/bindings/rtc/nxp,pcf2127.yaml
> > > > > b/Documentation/devicetree/bindings/rtc/nxp,pcf2127.yaml
> > > > > index 57eb0a58afa3..83656dd2f97f 100644
> > > > > --- a/Documentation/devicetree/bindings/rtc/nxp,pcf2127.yaml
> > > > > +++ b/Documentation/devicetree/bindings/rtc/nxp,pcf2127.yaml
> > > > > @@ -24,6 +24,16 @@ properties:
> > > > >    interrupts:
> > > > >      maxItems: 1
> > > > >  
> > > > > +  alarm-output-a:
> > > > 
> > > > nxp,alarm-output-a
> > > 
> > > Ok, this will be fixed for V2.
> > > 
> > 
> > Actually, this property has to be made more generic and thought
> > out.
> > There are multiple RTCs that have multiple interrupt pins where one
> > of
> > the pin can be used for different interrupt or clock output.

Hi,
the only example I could find of such a device is in rtc-pcf85363.c.
This device also has two interrupt pins, INT A/B, like the PCF2131.
However, in the pcf85363 driver, pin INT B is simply ignored, and all
interrupts are configured to go on INT A.

For the moment, I will simply modify my PCF2131 patches serie to mimic
the same behavior in V2. This simplifies things a lot, and support for
INT B pin could be added at a later stage (and also to pcf85363) if
anyone needs it (I don't).

Hugo.

> > With your binding, there is no way to separate which interrupt is
> > going
> > to which pin and so there is no way to get the alarm and BLF or the
> > watchdog on different pins and we certainly don't want to have a
> > property per interrupt type.
> 
> Hi,
> can you please suggest how you would prefer it to be done?
> 
> > Also, the documentation is missing the fact that the driver makes
> > having
> > one of the property mandatory.
> 
> I will add it.
> 
> Thank you, Hugo.
>