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[78.11.189.27]) by smtp.gmail.com with ESMTPSA id a16-20020a19f810000000b00494643db68fsm1952030lff.81.2022.10.04.08.05.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 04 Oct 2022 08:05:12 -0700 (PDT) Message-ID: <49daae86-e922-9a17-ebed-2a33a5eeb18e@linaro.org> Date: Tue, 4 Oct 2022 17:05:11 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.3.0 Subject: Re: [PATCH v1 17/17] drm/mediatek: Add mt8195-dpi support to drm_drv Content-Language: en-US To: Guillaume Ranquet , Michael Turquette , Kishon Vijay Abraham I , Matthias Brugger , Vinod Koul , Stephen Boyd , David Airlie , Rob Herring , Philipp Zabel , Krzysztof Kozlowski , Daniel Vetter , Chunfeng Yun , CK Hu , Jitao shi , Chun-Kuang Hu Cc: linux-mediatek@lists.infradead.org, dri-devel@lists.freedesktop.org, Pablo Sun , linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org, Mattijs Korpershoek , linux-arm-kernel@lists.infradead.org, linux-phy@lists.infradead.org, devicetree@vger.kernel.org References: <20220919-v1-0-4844816c9808@baylibre.com> <20220919-v1-17-4844816c9808@baylibre.com> From: Krzysztof Kozlowski In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 04/10/2022 13:55, Guillaume Ranquet wrote: >> No. You said what the code is doing. I think I understand this. You >> still do not need more compatibles. Your sentence did not clarify it >> because it did not answer at all to question "why". Why do you need it? >> >> Sorry, the change looks not correct. >> >> Best regards, >> Krzysztof >> > > I need a new compatible to adress the specifics of mt8195 in the mtk_dpi driver, > the change is in this series with: > [PATCH v1 16/17] drm/mediatek: dpi: Add mt8195 hdmi to DPI driver [1] But you do not have specifics of mt8195. I wrote it in the beginning. > > I then need to add that compatible to the "list" here in mtk_drm_drv. No, you do not... I checked the driver and there is no single need... or convince me you need. > I don't see a way around this unless I rewrite the way mtk_drm_drv works? Why rewrite? You have all compatibles in place. > > Maybe if I declare a new compatible that is generic to all mediatek > dpi variants? You were asked to use fallback. Don't create some fake fallbacks. Use existing ones. > and have all the dts specify the node with both the generic dpi and > the specific compatible? > > dpi@xxx { > compatible = "mediatek,dpi", "mediatek,mt8195-dpi"; I don't know what's this but certainly looks odd. Some wild-card compatible in front (not fallback) and none are documented. > ... > } > > Then I can "collapse" all the dpi related nodes in mtk_drm_drv under > "mediatek,dpi" ? > > I guess would have to do the change for all other components that are needed in > mtk_drm_drv (mmsys, aal, ccor, color, dither, dsc, gamma, mutex...). > > That's the only trivial way I can think of implementing this with the > current status > of the mtk_drm stack. > > Do you have any other ideas in mind? Use fallback of compatible device. That's the common pattern. Everywhere, Mediatek as well. Best regards, Krzysztof