Re: [PATCH v2 3/4] ARM: dts: armada-38x: Fix compatible string for gpios

From: "Pali Rohár" <pali@kernel.org>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: "Thierry Reding" <thierry.reding@gmail.com>,
	"Lee Jones" <lee.jones@linaro.org>,
	"Linus Walleij" <linus.walleij@linaro.org>,
	"Bartosz Golaszewski" <brgl@bgdev.pl>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
	"Andrew Lunn" <andrew@lunn.ch>,
	"Gregory Clement" <gregory.clement@bootlin.com>,
	"Sebastian Hesselbarth" <sebastian.hesselbarth@gmail.com>,
	"Marek Behún" <kabel@kernel.org>,
	linux-pwm@vger.kernel.org, linux-gpio@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 3/4] ARM: dts: armada-38x: Fix compatible string for gpios
Date: Sat, 16 Jul 2022 18:09:16 +0200	[thread overview]
Message-ID: <20220716160916.jp37siznitgzw6qf@pali> (raw)
In-Reply-To: <20220716150751.6yaknmo3qwusyy5h@pengutronix.de>

On Saturday 16 July 2022 17:07:51 Uwe Kleine-König wrote:
> On Sat, Jul 16, 2022 at 04:50:19PM +0200, Pali Rohár wrote:
> > On Saturday 16 July 2022 16:40:28 Uwe Kleine-König wrote:
> > > On Thu, Jul 14, 2022 at 08:33:27PM +0200, Pali Rohár wrote:
> > > > Armada 38x supports per CPU interrupts for gpios, like Armada XP. Pre-XP
> > > > variants like Armada 370 do not support per CPU interrupts for gpios.
> > > > 
> > > > So change compatible string for Armada 38x from "marvell,armada-370-gpio"
> > > > which indicates pre-XP variant to "marvell,armadaxp-gpio" which indicates
> > > > XP variant or new.
> > > > 
> > > > Driver gpio-mvebu.c which handles both pre-XP and XP variants already
> > > > provides support for per CPU interrupts on XP and newer variants.
> > > > 
> > > > Signed-off-by: Pali Rohár <pali@kernel.org>
> > > > Fixes: 7cb2acb3fbae ("ARM: dts: mvebu: Add PWM properties for armada-38x")
> > > > ---
> > > >  arch/arm/boot/dts/armada-38x.dtsi | 4 ++--
> > > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/arch/arm/boot/dts/armada-38x.dtsi b/arch/arm/boot/dts/armada-38x.dtsi
> > > > index df3c8d1d8f64..9343de6947b3 100644
> > > > --- a/arch/arm/boot/dts/armada-38x.dtsi
> > > > +++ b/arch/arm/boot/dts/armada-38x.dtsi
> > > > @@ -292,7 +292,7 @@
> > > >  			};
> > > >  
> > > >  			gpio0: gpio@18100 {
> > > > -				compatible = "marvell,armada-370-gpio",
> > > > +				compatible = "marvell,armadaxp-gpio",
> > > >  					     "marvell,orion-gpio";
> > > 
> > > If you can treat the XP variant as 370 and everything that is supposed
> > > to work on 370 works then, then maybe the right incarnation is:
> > > 
> > > 	compatible = "marvell,armadaxp-gpio", "marvell,armada-370-gpio", "marvell,orion-gpio";
> > > 
> > > ?
> > 
> > For pre-XP variants is "marvell,orion-gpio" enough and for XP + post-XP
> > is needed "marvell,armadaxp-gpio" (with possible "marvell,orion-gpio"
> > for backward compatibility).
> > 
> > So I do not see reason why to add "marvell,armada-370-gpio" nor what
> > value it brings.
> 
> If you boot an older kernel (i.e. one that doesn't support
> marvell,armadaxp-gpio, but does support marvell,armada-370-gpio), it

Is there such kernel version?

> will work better as there are relevant differences between
> marvell,orion-gpio and marvell,armada-370-gpio.

And if yes, do we really need this in DTS files for new kernel
versions? I can imagine that such change can be relevant for old LTS
kernel version, but not for new versions.

> For example some
> registers seem to have a different offset ...

armada-370-gpio is mapped to MVEBU_GPIO_SOC_VARIANT_ORION, so it will
get same offsets as orion-gpio. So no change.