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[212.78.193.212]) by smtp.gmail.com with ESMTPSA id g4-20020aa7c584000000b0052e2472f884sm930316edq.21.2023.09.21.07.45.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 21 Sep 2023 07:45:52 -0700 (PDT) Message-ID: Date: Thu, 21 Sep 2023 15:45:51 +0100 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] dt-bindings: mtd: jedec,spi-nor: Document support for more MT25QU parts Content-Language: en-US To: Geert Uytterhoeven , Rob Herring Cc: Michael Walle , Tudor Ambarus , Pratyush Yadav , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , Krzysztof Kozlowski , linux-mtd@lists.infradead.org, devicetree@vger.kernel.org, linux-renesas-soc@vger.kernel.org References: <363186079b4269891073f620e3e2353cf7d2559a.1669988238.git.geert+renesas@glider.be> <1503a3857107e3a4f34e0c7fb5dada39@walle.cc> <20221205163306.GB2012644-robh@kernel.org> From: Tudor Ambarus In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=1.2 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, RCVD_IN_SBL_CSS,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.6 X-Spam-Level: * X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Hi, Geert, Sorry for the delay, I just noticed this while cleaning the patchwork log. On 12/6/22 08:32, Geert Uytterhoeven wrote: > Hi Rob, > > On Mon, Dec 5, 2022 at 5:33 PM Rob Herring wrote: >> On Fri, Dec 02, 2022 at 02:56:01PM +0100, Geert Uytterhoeven wrote: >>> On Fri, Dec 2, 2022 at 2:50 PM Michael Walle wrote: >>>> Am 2022-12-02 14:37, schrieb Geert Uytterhoeven: >>>>> Document support for the Micron MT25QU256A and MT25QU512A Serial NOR >>>>> FLASHes. >>>>> >>>>> Merge the new entries with the existing entry for MT25QU02G. >>>>> >>>>> Signed-off-by: Geert Uytterhoeven >>>>> --- >>>>> mt25qu512a is already in active use, causing "make dtbs_check" errors. >>>>> mt25qu256a is supported by the Linux spi-nor driver, but there are no >>>>> upstream users yet. >>>> >>>> Is it encouraged to use the specific compatible with SPI-NOR flashes? >>>> As far as I know it isn't. The spi-nor subsys tries hard to identify >>>> any flashes at runtime and any additional information in the device tree >>>> is used as a last resort (just for flashes which doesn't support the >>>> read jedec id command yet). And usually boards have different sources >>>> for flash chips, so hardcoding a particular part in the device tree >>>> doesn't make sense. >>> >>> Thanks, I am aware there have been pushbacks when trying to >>> document more compatible values. >>> >>> IMHO either all or none of them should be documented. >>> If device-specific compatible values are discouraged, the bindings >>> should be updated to reflect that, and document a single compatible >>> value ("jedec,spi-nor") only. >> >> That's already allowed, so there's your answer. > > It's indeed allowed, but the alternative is documented, too (for some > values). > >> The caveat is don't be adding them later to your DT when you find an >> issue and new quirk properties will probably be rejected. > > Adding them later to your DT when you find an issue makes no sense, > as that breaks compatibility with older DTBs. > We won't break compatibility with older DTBs if we use a list of compatibles. First the vendor specific one which will use some quirks, and if that's not available, have as second the generic jedec,spi-nor to fallback to. Cheers, ta