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[92.176.231.205]) by smtp.gmail.com with ESMTPSA id f19-20020a7bc8d3000000b00405959469afsm16076183wml.3.2023.10.11.00.34.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Oct 2023 00:34:28 -0700 (PDT) From: Javier Martinez Canillas To: Rob Herring Cc: devicetree@vger.kernel.org, Conor Dooley , Thomas Zimmermann , Krzysztof Kozlowski , linux-kernel@vger.kernel.org, Maxime Ripard , Geert Uytterhoeven , dri-devel@lists.freedesktop.org Subject: Re: [PATCH 8/8] dt-bindings: display: Add SSD132x OLED controllers In-Reply-To: <87v8bdslx7.fsf@minerva.mail-host-address-is-not-set> References: <20231009183522.543918-1-javierm@redhat.com> <20231009183522.543918-9-javierm@redhat.com> <20231010165838.GA1039918-robh@kernel.org> <87v8bdslx7.fsf@minerva.mail-host-address-is-not-set> Date: Wed, 11 Oct 2023 09:34:28 +0200 Message-ID: <87sf6hsjcr.fsf@minerva.mail-host-address-is-not-set> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Javier Martinez Canillas writes: > Rob Herring writes: > > Hello Rob, > > Thanks a lot for your feedback. > >> On Mon, Oct 09, 2023 at 08:34:22PM +0200, Javier Martinez Canillas wrote: >>> Add a Device Tree binding schema for the OLED panels based on the Solomon >>> SSD132x family of controllers. >> >> Looks like the same binding as solomon,ssd1307fb.yaml. Why a different >> binding? Why does that binding need a slew of custom properties and here >> you don't? >> > > It's a sub-set of it. Because only the minimum required properties are > defined. But also, is a clean slate schema because the old ssd1307fb fbdev > driver only supports the Solomon SSD130x family, so there is no need to > follow the existing solomon,ssd1307fb.yaml nor the need for backward compat. > I think this answer was a little sparse, let me elaborate a bit. The Solomon display controllers are quite flexible, so that could be used with different OLED panels. And the ssd1307fb binding schema defines a set of properties that are almost a 1:1 mapping from properties to the configuration registers. This makes the driver to support most SSD130x controller + panel configurations but at the expense of making the binding more complicated (a slew of custom propertie as you pointed out). Now, as mentioned this is support for greyscale Solomon controllers (the old fbdev driver only supports monochrome controllers) so we don't care about DT backward compatibility. I decided for now to keep the binding at a minimum and be more opinionated in the driver with having what I think are sane defaults for most of the config registers. If there is a need to expose any of this configuration as DT properties, then we can later added it share some of the existing solomon,ssd1307fb.yaml custom properties and move them to a common schema. We can always change the driver in the future anyways, but we can't do the same with the DT binding schema since that is considered an ABI. -- Best regards, Javier Martinez Canillas Core Platforms Red Hat