Re: [PATCH v8 5/7] can: ctucanfd: CTU CAN FD open-source IP core - platform/SoC support. - Marc Kleine-Budde

From: Marc Kleine-Budde <mkl@pengutronix.de>
To: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>,
	linux-can@vger.kernel.org,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	Oliver Hartkopp <socketcan@hartkopp.net>,
	Wolfgang Grandegger <wg@grandegger.com>,
	David Miller <davem@davemloft.net>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Carsten Emde <c.emde@osadl.org>,
	armbru@redhat.com, netdev <netdev@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Marin Jerabek <martin.jerabek01@gmail.com>,
	Ondrej Ille <ondrej.ille@gmail.com>,
	Jiri Novak <jnovak@fel.cvut.cz>,
	Jaroslav Beran <jara.beran@gmail.com>,
	Petr Porazil <porazil@pikron.com>, Pavel Machek <pavel@ucw.cz>,
	Drew Fustini <pdp7pdp7@gmail.com>
Subject: Re: [PATCH v8 5/7] can: ctucanfd: CTU CAN FD open-source IP core - platform/SoC support.
Date: Wed, 4 May 2022 08:34:02 +0200	[thread overview]
Message-ID: <20220504063402.deowqy5lnmgg2mfy@pengutronix.de> (raw)
In-Reply-To: <202205031707.21405.pisa@cmp.felk.cvut.cz>

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On 03.05.2022 17:07:21, Pavel Pisa wrote:
> Hello Geert,
> 
> On Tuesday 03 of May 2022 13:37:46 Geert Uytterhoeven wrote:
> > Hi Pavel,
> > > --- /dev/null
> > > +++ b/drivers/net/can/ctucanfd/ctucanfd_platform.c
> > >
> > > +/* Match table for OF platform binding */
> > > +static const struct of_device_id ctucan_of_match[] = {
> > > +       { .compatible = "ctu,ctucanfd-2", },
> >
> > Do you need to match on the above compatible value?
> > The driver seems to treat the hardware the same, and the DT
> > bindings state the compatible value below should always be present.
> 
> I would keep it because there will be newer revisions and releases
> of the core and I consider "ctu,ctucanfd" as the match to generic
> one with maximal attempt to adjust to the version from provided
> info registers but identification with the fixed version
> "ctu,ctucanfd-2" ensures that some old hardware which is
> in the wild is directly recognized even at /sys level
> and if we need to do some workarounds for autodetection
> etc. it can be recognized.

As Geert said:
- There are 2 bindings in the driver which are (currently) treated the
  same.
- The binding documentation says devices must always have the
  ctu,ctucanfd compatible.

This means (currently) the ctu,ctucanfd-2 is not needed in the driver.
We can add it back once we need it.

Or are there devices that have a compatible of ctu,ctucanfd-2 without
stating to be compatible with ctu,ctucanfd?

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |

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