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[2001:14bb:ae:539c:1782:dd68:b0c1:c1a4]) by smtp.gmail.com with ESMTPSA id k12-20020ac24f0c000000b0048b03b4b018sm1325108lfr.283.2022.08.16.02.42.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 16 Aug 2022 02:42:40 -0700 (PDT) Message-ID: Date: Tue, 16 Aug 2022 12:42:39 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.12.0 Subject: Re: [PATCH 06/12] riscv: dts: allwinner: Add the D1 SoC base devicetree Content-Language: en-US To: =?UTF-8?Q?Jernej_=c5=a0krabec?= , Samuel Holland , Chen-Yu Tsai , linux-sunxi@lists.linux.dev, Palmer Dabbelt , Paul Walmsley , Albert Ou , linux-riscv@lists.infradead.org, =?UTF-8?Q?Heiko_St=c3=bcbner?= Cc: Rob Herring , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Krzysztof Kozlowski References: <20220815050815.22340-1-samuel@sholland.org> <5593349.DvuYhMxLoT@jernej-laptop> <3881930.ZaRXLXkqSa@diego> <2249129.ElGaqSPkdT@jernej-laptop> From: Krzysztof Kozlowski In-Reply-To: <2249129.ElGaqSPkdT@jernej-laptop> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16/08/2022 12:25, Jernej Škrabec wrote: > Dne torek, 16. avgust 2022 ob 11:12:05 CEST je Heiko Stübner napisal(a): >> Am Dienstag, 16. August 2022, 09:49:58 CEST schrieb Jernej Škrabec: >>> Dne torek, 16. avgust 2022 ob 09:41:45 CEST je Krzysztof Kozlowski > napisal(a): >>>> On 15/08/2022 08:08, Samuel Holland wrote: >>>>> + >>>>> + de: display-engine { >>>>> + compatible = "allwinner,sun20i-d1-display-engine"; >>>>> + allwinner,pipelines = <&mixer0>, <&mixer1>; >>>>> + status = "disabled"; >>>>> + }; >>>>> + >>>>> + osc24M: osc24M-clk { >>>> >>>> lowercase >>>> >>>>> + compatible = "fixed-clock"; >>>>> + clock-frequency = <24000000>; >>>> >>>> This is a property of the board, not SoC. >>> >>> SoC needs 24 MHz oscillator for correct operation, so each and every board >>> has it. Having it here simplifies board DT files. >> >> I guess the oscillator is a separate component on each board, right? > > Correct. > >> And DT obvious is meant to describe the hardware - independently from >> implementation-specific choices. > > There is no choice in this case. 24 MHz crystal has to be present. > > FWIW, including crystal node in SoC specific DTSI is already common pattern in > Allwinner ARM SoC DTSI files. > >> >> Starting to discuss which exceptions to allow then might lead to even more >> exceptions. >> >> Also having to look for a board-component in the soc dtsi also is surprising >> if one gets to the party later on :-) . > > As I said, if one is accustomed to Allwinner ARM DT development, it would be > more surprising to include 24 MHz crystal node in each and every board DT. It's same everywhere. Allwinner, Exynos, iMX, Qualcomm. Everywhere this is a part of the board, so even if oscillator frequency is fixed (as in 99% of cases although some SoCs I think might just allow to implement one of few), still this is a property of the board. Because: 1. DTSI describes the SoC part, not board. 2. So the DTS developer is a bit more conscious about his design. Keeping things in SoC DTSI just because it simplifies DTS is not correct IMHO. So again - like in several other cases - minimum the frequency is property of the board, not the SoC DTSI. Everywhere. Allwinner is not special to receive exceptions. Best regards, Krzysztof