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([2a01:e0a:982:cbb0:b158:3e69:8736:455d]) by smtp.gmail.com with ESMTPSA id y9-20020adfdf09000000b0031122bd3c82sm3785271wrl.17.2023.06.21.01.04.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 21 Jun 2023 01:04:30 -0700 (PDT) Message-ID: <6fe5dfb6-5f18-feca-a2e7-8cfb78627e01@linaro.org> Date: Wed, 21 Jun 2023 10:04:28 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 From: Neil Armstrong Reply-To: neil.armstrong@linaro.org Subject: Re: [PATCH v2 2/2] arm64: dts: meson-t7-a311d2-khadas-vim4: add initial device-tree Content-Language: en-US To: Conor Dooley , Lucas Tanure Cc: Krzysztof Kozlowski , Yixun Lan , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Jerome Brunet , Kevin Hilman , Nick , Artem , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-amlogic@lists.infradead.org, linux-arm-kernel@lists.infradead.org References: <20230620134857.238941-1-tanure@linux.com> <20230620134857.238941-3-tanure@linux.com> <76a7f819-f3d2-d39d-1bc9-f1e7f837fd22@linaro.org> <20230621-barber-enjoyably-04806271daea@wendy> Organization: Linaro Developer Services In-Reply-To: <20230621-barber-enjoyably-04806271daea@wendy> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 21/06/2023 10:01, Conor Dooley wrote: > On Wed, Jun 21, 2023 at 08:37:02AM +0100, Lucas Tanure wrote: >> On Wed, Jun 21, 2023 at 7:02 AM Krzysztof Kozlowski >> wrote: >>> >>> On 21/06/2023 00:09, Yixun Lan wrote: >>>>> + apb4: bus@fe000000 { >>>>> + compatible = "simple-bus"; >>>>> + reg = <0x0 0xfe000000 0x0 0x480000>; >>>>> + #address-cells = <2>; >>>>> + #size-cells = <2>; >>>>> + ranges = <0x0 0x0 0x0 0xfe000000 0x0 0x480000>; >>>>> + >>>>> + uart_A: serial@78000 { >>>>> + compatible = "amlogic,meson-t7-uart", >>>> ~~~~~~~~~~~~~~~~~ >>>> if you introduce new compatible string, then at least you need to document it >>>> so Documentation/devicetree/bindings/serial/amlogic,meson-uart.yaml need to be updated >>>> >>>> but my qeustion here, why bother introducing new compatible string if nothing >>>> changed with the compatible data? given the uart is same IP with g12a, can't we just >>>> use "amlogic,meson-g12-uart" for this? no only it will reduce the structure length of >>>> meson_uart_dt_match[], but also relieve maintainer's review burden? >>> >>> https://elixir.bootlin.com/linux/v6.1-rc1/source/Documentation/devicetree/bindings/writing-bindings.rst#L42 >>> >>> Best regards, >>> Krzysztof >>> >> Hi, I did not understand the recommendation here. >> Can I add "amlogic,meson-t7-uart" without Documentation changes? > > No, you can't. > >> I think Yes, as I can see a few compatible strings in dts that don't >> exist anywhere else. > > Aye, but we do not want to propagate that. New stuff should not be > adding undocumented compatibles, and those that are undocumented should > be documented. Documentation is ongoing, it takes time ! Neil > >> My idea here is to add "amlogic,meson-t7-uart" for future use if ever >> created, like if we find a bug in the future that is only relevant to >> T7 soc. >> But for now, fallback to s4 uart, as it seems to be the same controller. >> >> >From Krzysztof said in the writing-bindings.rst, I am following the rules. >> >> So, what's the path forward here? > > You are following the rules from the dts point of view, you just need a > 3rd patch in which you document the pattern you have added here in > amlogic,meson-uart.yaml. It is probably something like: > + - items: > + - const: amlogic,meson-t7-uart > + - const: amlogic,meson-s4-uart > But I have not tested that, I just wrote that in my mail client. > > Cheers, > Conor.