From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boris Brezillon Subject: Re: [PATCH v1 2/2] arm: dts: mt2701: add nor flash node Date: Fri, 13 Jan 2017 17:28:25 +0100 Message-ID: <20170113172825.75d545a3@bbrezillon> References: <1484291609-20195-1-git-send-email-guochun.mao@mediatek.com> <1484291609-20195-3-git-send-email-guochun.mao@mediatek.com> <20170113151747.6bc85245@bbrezillon> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Marek Vasut Cc: Matthias Brugger , Guochun Mao , David Woodhouse , Brian Norris , Richard Weinberger , Cyrille Pitchen , Rob Herring , Mark Rutland , Russell King , linux-mtd@lists.infradead.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org List-Id: devicetree@vger.kernel.org On Fri, 13 Jan 2017 17:13:55 +0100 Marek Vasut wrote: > On 01/13/2017 04:12 PM, Matthias Brugger wrote: > > > > > > On 13/01/17 15:17, Boris Brezillon wrote: > >> On Fri, 13 Jan 2017 15:13:29 +0800 > >> Guochun Mao wrote: > >> > >>> Add Mediatek nor flash node. > >>> > >>> Signed-off-by: Guochun Mao > >>> --- > >>> arch/arm/boot/dts/mt2701-evb.dts | 25 +++++++++++++++++++++++++ > >>> arch/arm/boot/dts/mt2701.dtsi | 12 ++++++++++++ > >>> 2 files changed, 37 insertions(+) > >>> > >>> diff --git a/arch/arm/boot/dts/mt2701-evb.dts > >>> b/arch/arm/boot/dts/mt2701-evb.dts > >>> index 082ca88..85e5ae8 100644 > >>> --- a/arch/arm/boot/dts/mt2701-evb.dts > >>> +++ b/arch/arm/boot/dts/mt2701-evb.dts > >>> @@ -24,6 +24,31 @@ > >>> }; > >>> }; > >>> > >>> +&nor_flash { > >>> + pinctrl-names = "default"; > >>> + pinctrl-0 = <&nor_pins_default>; > >>> + status = "okay"; > >>> + flash@0 { > >>> + compatible = "jedec,spi-nor"; > >>> + reg = <0>; > >>> + }; > >>> +}; > >>> + > >>> +&pio { > >>> + nor_pins_default: nor { > >>> + pins1 { > >>> + pinmux = , > >>> + , > >>> + , > >>> + , > >>> + , > >>> + ; > >>> + drive-strength = ; > >>> + bias-pull-up; > >>> + }; > >>> + }; > >>> +}; > >>> + > >>> &uart0 { > >>> status = "okay"; > >>> }; > >>> diff --git a/arch/arm/boot/dts/mt2701.dtsi > >>> b/arch/arm/boot/dts/mt2701.dtsi > >>> index bdf8954..1eefce4 100644 > >>> --- a/arch/arm/boot/dts/mt2701.dtsi > >>> +++ b/arch/arm/boot/dts/mt2701.dtsi > >>> @@ -227,6 +227,18 @@ > >>> status = "disabled"; > >>> }; > >>> > >>> + nor_flash: spi@11014000 { > >>> + compatible = "mediatek,mt2701-nor", > >>> + "mediatek,mt8173-nor"; > >> > >> Why define both here? Is "mediatek,mt8173-nor" really providing a > >> subset of the features supported by "mediatek,mt2701-nor"? > >> > > > > I think even if the ip block is the same, we should provide both > > bindings, just in case in the future we find out that mt2701 has some > > hidden bug, feature or bug-feature. This way even if we update the > > driver, we stay compatible with older device tree blobs in the wild. > > > > We can drop the mt2701-nor in the bindings definition if you want. Oh, sorry, I misunderstood. What I meant is that if you want to list/support all possible compatibles, maybe you should just put one compatible in your DT and patch your driver (+ binding doc) to define all of them. > > This exactly. We should have a DT compat in the form: > compatible = "vendor,-block", "vendor,-block"; > Then if we find a problem in the future, we can match on the > "vendor,-block" and still support the old DTs. Not sure it's only in term of whose IP appeared first. My understanding is that it's a way to provide inheritance. For example: ",", ","; or ",",","; BTW, which one is the oldest between mt8173 and mt2701? :-)