On 01/13/2017 05:28 PM, Boris Brezillon wrote: > On Fri, 13 Jan 2017 17:13:55 +0100 > Marek Vasut <marek.vasut@xxxxxxxxx> 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 <guochun.mao@xxxxxxxxxxxx> wrote: >>>> >>>>> Add Mediatek nor flash node. >>>>> >>>>> Signed-off-by: Guochun Mao <guochun.mao@xxxxxxxxxxxx> >>>>> --- >>>>> 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 = <MT2701_PIN_240_EXT_XCS__FUNC_EXT_XCS>, >>>>> + <MT2701_PIN_241_EXT_SCK__FUNC_EXT_SCK>, >>>>> + <MT2701_PIN_239_EXT_SDIO0__FUNC_EXT_SDIO0>, >>>>> + <MT2701_PIN_238_EXT_SDIO1__FUNC_EXT_SDIO1>, >>>>> + <MT2701_PIN_237_EXT_SDIO2__FUNC_EXT_SDIO2>, >>>>> + <MT2701_PIN_236_EXT_SDIO3__FUNC_EXT_SDIO3>; >>>>> + drive-strength = <MTK_DRIVE_4mA>; >>>>> + 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. Uh, what ? I lost you here :-) >> This exactly. We should have a DT compat in the form: >> compatible = "vendor,<soc>-block", "vendor,<oldest-compat-soc>-block"; >> Then if we find a problem in the future, we can match on the >> "vendor,<soc>-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: > > "<soc-vendor>,<ip-version>", "<ip-vendor>,<ip-version>"; > > or > > "<soc-vendor>,<full-featured-ip-version>","<soc-vendor>,<basic-feature-ip-version>"; > > BTW, which one is the oldest between mt8173 and mt2701? :-) And that's another thing and I agree with you, but I don't think that's what we're discussing in this thread. But (!), OT, I think we should codify the rules in Documentation/ . This discussion came up multiple times recently. And my question still stands, what do we put into the DT here, IMO compatible = "mediatek,mt2701-nor", "mediatek,mt8173-nor"; and what goes into the binding document ? I guess both too ? -- Best regards, Marek Vasut -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html