linux-kernel - Re: [PATCH v2 2/4] nfc: pn532_uart: Add NXP PN532 to devicetree docs

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Date:   Fri, 19 Oct 2018 11:12:21 +0200
From:   Lars Poeschel <poeschel@...onage.de>
To:     Rob Herring <robh@...nel.org>
Cc:     Marcel Holtmann <marcel@...tmann.org>,
        devicetree <devicetree@...r.kernel.org>,
        Mark Rutland <mark.rutland@....com>,
        Peter Rosin <peda@...ntia.se>,
        Vadim Pasternak <vadimp@...lanox.com>,
        Lei YU <mine260309@...il.com>,
        Andreas Färber <afaerber@...e.de>,
        Jonathan Neuschäfer <j.neuschaefer@....net>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/4] nfc: pn532_uart: Add NXP PN532 to devicetree docs

On Thu, Oct 18, 2018 at 03:41:29PM -0500, Rob Herring wrote:
> On Thu, Oct 18, 2018 at 05:03:13PM +0200, Marcel Holtmann wrote:
> > Hi Lars,
> > 
> > > Add pn532 to the trivial-devices.txt binding doc.
> > > 
> > > Signed-off-by: Lars Poeschel <poeschel@...onage.de>
> > > ---
> > > Documentation/devicetree/bindings/trivial-devices.txt | 1 +
> > > 1 file changed, 1 insertion(+)
> > > 
> > > diff --git a/Documentation/devicetree/bindings/trivial-devices.txt b/Documentation/devicetree/bindings/trivial-devices.txt
> > > index 763a2808a95c..c580be08a380 100644
> > > --- a/Documentation/devicetree/bindings/trivial-devices.txt
> > > +++ b/Documentation/devicetree/bindings/trivial-devices.txt
> > > @@ -172,6 +172,7 @@ nxp,pcf2129		Real-time clock
> > > nxp,pcf8523		Real-time Clock
> > > nxp,pcf8563		Real-time clock/calendar
> > > nxp,pcf85063		Tiny Real-Time Clock
> > > +nxp,pn532-uart		NXP PN532 NFC-/RFID-Chip, using UART interface
> > 
> > is this really such a trivial device? It doesn’t require any GPIO to enable / reset the NFC chip?

It does not require any additional things like GPIO or Interrupts. These
are optional and at the moment not supported by the driver.

> Considering it supports multiple interfaces, it is not.
> 
> The '-uart' can be dropped and the same compatible used for any 
> of the bus connections because the device is bound based on the bus 
> type.

Ok.
I drop the '-uart' part from the compatible string and provide a
seperate, little binding doc, documenting the compatible string used.

But does this also have consequences for the already existing -i2c
driver? This one uses 'nxp,pn532-i2c' as compatible string.

Thanks,
Lars