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([2a01:e0a:982:cbb0:9dc0:6c46:415c:5f8b]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4349ca82957sm66277205e9.33.2024.11.25.07.37.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 25 Nov 2024 07:37:36 -0800 (PST) Message-ID: <48f3bb08-a591-401c-bc0c-6af0506a1b1f@linaro.org> Date: Mon, 25 Nov 2024 16:37:35 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: neil.armstrong@linaro.org Reply-To: neil.armstrong@linaro.org Subject: Re: [PATCH 2/5] gpu: drm: adp: Add Apple Display Pipe driver To: Hector Martin , Sasha Finkelstein Cc: Sven Peter , Alyssa Rosenzweig , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Jessica Zhang , asahi@lists.linux.dev, linux-arm-kernel@lists.infradead.org, dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Janne Grunau References: <20241124-adpdrm-v1-0-3191d8e6e49a@gmail.com> <20241124-adpdrm-v1-2-3191d8e6e49a@gmail.com> <10d0aa88-de2e-4856-a137-301519e58b2d@linaro.org> Content-Language: en-US, fr Autocrypt: addr=neil.armstrong@linaro.org; keydata= xsBNBE1ZBs8BCAD78xVLsXPwV/2qQx2FaO/7mhWL0Qodw8UcQJnkrWmgTFRobtTWxuRx8WWP GTjuhvbleoQ5Cxjr+v+1ARGCH46MxFP5DwauzPekwJUD5QKZlaw/bURTLmS2id5wWi3lqVH4 BVF2WzvGyyeV1o4RTCYDnZ9VLLylJ9bneEaIs/7cjCEbipGGFlfIML3sfqnIvMAxIMZrvcl9 qPV2k+KQ7q+aXavU5W+yLNn7QtXUB530Zlk/d2ETgzQ5FLYYnUDAaRl+8JUTjc0CNOTpCeik 80TZcE6f8M76Xa6yU8VcNko94Ck7iB4vj70q76P/J7kt98hklrr85/3NU3oti3nrIHmHABEB AAHNKk5laWwgQXJtc3Ryb25nIDxuZWlsLmFybXN0cm9uZ0BsaW5hcm8ub3JnPsLAkQQTAQoA OwIbIwULCQgHAwUVCgkICwUWAgMBAAIeAQIXgBYhBInsPQWERiF0UPIoSBaat7Gkz/iuBQJk Q5wSAhkBAAoJEBaat7Gkz/iuyhMIANiD94qDtUTJRfEW6GwXmtKWwl/mvqQtaTtZID2dos04 YqBbshiJbejgVJjy+HODcNUIKBB3PSLaln4ltdsV73SBcwUNdzebfKspAQunCM22Mn6FBIxQ GizsMLcP/0FX4en9NaKGfK6ZdKK6kN1GR9YffMJd2P08EO8mHowmSRe/ExAODhAs9W7XXExw UNCY4pVJyRPpEhv373vvff60bHxc1k/FF9WaPscMt7hlkbFLUs85kHtQAmr8pV5Hy9ezsSRa GzJmiVclkPc2BY592IGBXRDQ38urXeM4nfhhvqA50b/nAEXc6FzqgXqDkEIwR66/Gbp0t3+r yQzpKRyQif3OwE0ETVkGzwEIALyKDN/OGURaHBVzwjgYq+ZtifvekdrSNl8TIDH8g1xicBYp QTbPn6bbSZbdvfeQPNCcD4/EhXZuhQXMcoJsQQQnO4vwVULmPGgtGf8PVc7dxKOeta+qUh6+ SRh3vIcAUFHDT3f/Zdspz+e2E0hPV2hiSvICLk11qO6cyJE13zeNFoeY3ggrKY+IzbFomIZY 4yG6xI99NIPEVE9lNBXBKIlewIyVlkOaYvJWSV+p5gdJXOvScNN1epm5YHmf9aE2ZjnqZGoM Mtsyw18YoX9BqMFInxqYQQ3j/HpVgTSvmo5ea5qQDDUaCsaTf8UeDcwYOtgI8iL4oHcsGtUX oUk33HEAEQEAAcLAXwQYAQIACQUCTVkGzwIbDAAKCRAWmrexpM/4rrXiB/sGbkQ6itMrAIfn M7IbRuiSZS1unlySUVYu3SD6YBYnNi3G5EpbwfBNuT3H8//rVvtOFK4OD8cRYkxXRQmTvqa3 3eDIHu/zr1HMKErm+2SD6PO9umRef8V82o2oaCLvf4WeIssFjwB0b6a12opuRP7yo3E3gTCS KmbUuLv1CtxKQF+fUV1cVaTPMyT25Od+RC1K+iOR0F54oUJvJeq7fUzbn/KdlhA8XPGzwGRy 4zcsPWvwnXgfe5tk680fEKZVwOZKIEuJC3v+/yZpQzDvGYJvbyix0lHnrCzq43WefRHI5XTT QbM0WUIBIcGmq38+OgUsMYu4NzLu7uZFAcmp6h8g Organization: Linaro In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Hector, On 25/11/2024 15:24, Hector Martin wrote: > > > On 2024/11/25 20:24, Sasha Finkelstein wrote: >> On Mon, 25 Nov 2024 at 09:50, Neil Armstrong wrote: >>> >>> So this controller only supports a single mode ??????? >>> >> Most likely. On all devices it is connected to a single built-in display. > > More specifically, the controller obviously supports multiple modes but > it is pre-initialized by the bootloader for the single hardwired > display's only mode. So as far as the driver is concerned, there is a > single possible mode, and there's no point in trying to be more generic > if there is no hardware that would use that. I totally got the point, I just asked to slightly change the design to fit the overall DRM/DSI/Panel architecture. > > In general, it is not possible/practical to be generic for reverse > engineered hardware with no specs documenting how to drive it > generically. You just can't know how to implement the options that are > never used in practice. I spent a lot of time on exceptions to this rule > for the GPIO and SPI controllers, and that's not going to happen for > more complex hardware like MIPI DSI. I'm fine with the overall actual design since it's a special usecase for a special display present on only a few SKUs. Nevertheless, as Maxime expressed, you should still try to fit nicely on the abstractions, or change the abstractions. Neil > > - Hector >