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Thu, 05 Nov 2026 12:12:23 -0800 (PST) Received: from localhost ([82.77.126.113]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48fecac1caesm11108369f8f.17.2026.11.05.12.12.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Nov 2026 12:12:22 -0800 (PST) From: Daniel Matyas To: dri-devel@lists.freedesktop.org Cc: Daniel Matyas , linux-staging@lists.linux.dev, Andy Shevchenko , Greg Kroah-Hartman , Alex Lanzano , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Conor Dooley , Rob Herring , Krzysztof Kozlowski , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Nam Cao , linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, devicetree@vger.kernel.org Subject: [RFC] staging: fbtft: Moving fb_ili9341 (and others) to DRM Date: Thu, 5 Nov 2026 22:11:53 +0200 Message-ID: <20261105201154.37294-2-matyasdaniel006@gmail.com> X-Mailer: git-send-email 2.55.0 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi, I'm looking at the fbtft TODO (convert drivers to DRM) and want to check whether fb_ili9341 can be dropped. Findings against v7.4-rc1: 1. fb_ili9341's init sequence is the MI0283QT-9A one. Comparing register writes with drivers/gpu/drm/tiny/mi0283qt.c, the values are identical, including the default gamma tables. Differences I found: - mi0283qt writes EN3GAM (0xF2) = 0x08; the fbtft write is commented out. - mi0283qt always sets MADCTL BGR; fbtft makes it configurable (bgr=). - fbtft rotate=270 also sets ML; mi0283qt does not. - Rotation maps as DRM rotation = fbtft rotate - 90 (mod 360). - fbtft also offers runtime gamma adjustment. 2. fb_ili9341 registers the compatible "ilitek,ili9341", which is also the fallback in the dt-schema binding, so it can match nodes that the DRM drivers claim via their specific compatibles. 3. In-tree users: no defconfig enables FB_TFT. canaan_kd233 (62363a8e2f56, Feb 2021) has a status = "disabled" panel node compatible with "canaan,kd233-tft", "ilitek,ili9341". It predates the first DRM driver accepting ilitek,ili9341 (5a04227326b0, Jul 2021), and none of the DRM drivers match canaan,kd233-tft. fbtft requests "dc" and "reset" GPIOs, which fits that node. I haven't tried binding it. I suppose that, if the board is used, then it is built against the fbtft driver. 4. fb_ili9341 has had only style/mechanical changes in recent years. Questions: a) Is removing fb_ili9341 acceptable, pointing users of other ILI9341 modules to panel-mipi-dbi? The KD233 node would then have no driver. b) Or should KD233 panel support go into a DRM driver first? I don't have its init sequence or physical size, or the board... c) Is removal of all of fbtft already planned? d) Several other fbtft drivers have drm counterparts. Should I inspect those to see if removal is needed? I have not tested on hardware. Thanks, Daniel M