From nobody Thu Sep 24 22:57:37 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C3DF0293B75; Fri, 18 Sep 2026 20:51:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789764700; cv=none; b=CTeiLv04BP5by5YOuRMcwanZnIjeCKR0hiiMYznZ59BfD+aUvmCV7hxZrCMSgbJd3vW4FnYz5MlXWHEXtjjyYxsUPl/Pnly+5BMgZSHXdi+zO8aEgJ74nu2c4A6qfmoqqDldwAkSDb6acoXz3rrYAZGTK3/HlsUMnRwq45RJTlQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789764700; c=relaxed/simple; bh=QCIJObhinfLLP3u8ve1yUqV6GMr/mmcL9F5ebTD8qqo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=ApnyWwzVBTPSskokw9D5R45uoxdIPaV1WUExz90qGVO1QKkinsEveI6MyYmxNwEwe29VRt7A+fyZF8z+hU4wAw+n/jqCjntwqfZlePtojiwgyfbhVU8deFMUx11v7pTXGLAbTFaDuU28DvvrCVDRDAkWaZuY1B3zePqTDULvIJ4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fdcp6bEs; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fdcp6bEs" Received: by smtp.kernel.org (Postfix) with ESMTPS id 57618C2BCB8; Fri, 18 Sep 2026 20:51:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1789764700; bh=QCIJObhinfLLP3u8ve1yUqV6GMr/mmcL9F5ebTD8qqo=; h=From:Date:Subject:To:Cc:Reply-To:From; b=fdcp6bEs+hbnE3DeTTyKxZf0XWRDOIAYoM8Nv6qphc/EvBFO+jB2U5g9uNCiXdEPL u4ax7UL0CxKHY8LwJjrpuhB3dqXVEGIWV1WBvTLnzwPL04df53rJObOmeWBqsg08AO GyA+bWNEN3jevDpW2bT33c5EUZguC5nNNTtD4FGxiZQb9RGnCbEQSmr6kqeQrtFfQb 5/5Y/sVF8WS6kpuPS4/zovcekmi1P01pIkkRXWIYLBVnBUrm/uExTHApFjgz5C+Asb zQ3IL9ZdWZOZYPZq1sSPdcumWRZ5UZ1ZTdefxluRa3EzgrZErJuFtRVftYVqzl25ko 6x85mtEx/ViAA== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 40A8FC982D8; Fri, 18 Sep 2026 20:51:40 +0000 (UTC) From: Avalon Vargas via B4 Relay Date: Fri, 18 Sep 2026 14:51:36 -0600 Subject: [PATCH] arm64: dts: qcom: Fix backlight control on Dell Inspiron 7441 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260918-dell7441-backlight-v1-1-f7646ae30cae@est.una.ac.cr> X-B4-Tracking: v=1; b=H4sIAAAAAAAC/yWMQQ7CIBBFr9LMWiKQRqtXMS4GmMIoUgNoTJreX dDl+/nvrVAoMxU4DytkenPhJTVQuwFswORJsGsMWuqDPKlJOIrxOI5KGLT3yD5UIaVWGmfpUE3 QxGemmT+/6OX65/IyN7K1l/rDYCFhMiYb+rRk9pz2DyyVMmzbF4efdZOWAAAA X-Change-ID: 20260918-dell7441-backlight-00212af0da18 To: Bjorn Andersson , Konrad Dybcio , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Laurentiu Tudor Cc: Rafael Dettogni Guariento , Val Packett , Bryan O'Donoghue , Neil Armstrong , dri-devel@lists.freedesktop.org, Konrad Dybcio , linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Avalon Vargas X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1789764699; l=3410; i=avalon.vargas.centeno@est.una.ac.cr; s=avalon-una-20260914; h=from:subject:message-id; bh=u1ZQbSAfwqgtkK6O3ck7wrXaPpGTJgsfRfeZp/Dum9o=; b=NSvKR5ItR/Oz/hETmop6P86/UAhimlz7RdxF5dxrGq3/54atF0ntlj1lafEpn/GUPJJTR4ioM bovpfN74o6jDNqbjWke+hZ3L72DSQWyc4iXOt/A/6wv9tmLOCaSP5FF X-Developer-Key: i=avalon.vargas.centeno@est.una.ac.cr; a=ed25519; pk=I7FZ301yhA9Jl2LReBEqv+9LUrd5zi397CIT2gTB6RE= X-Endpoint-Received: by B4 Relay for avalon.vargas.centeno@est.una.ac.cr/avalon-una-20260914 with auth_id=1032 X-Original-From: Avalon Vargas Reply-To: avalon.vargas.centeno@est.una.ac.cr From: Avalon Vargas The AUO B140QAX01.H panel on tested Dell Inspiron 14 Plus 7441 units advertises PWM brightness control but not AUX brightness setting. Without a backlight described in the device tree, the panel falls back to the AUX helper, which registers a backlight with max_brightness=3D0. Brightness adjustment is consequently unavailable. Enable PMK8550 PWM channel 0, route it through GPIO5, and connect a PWM backlight to the panel. Provide an interpolated brightness table with 101 levels and a default level of 80. Fixes: e7733b42111c ("arm64: dts: qcom: Add support for Dell Inspiron 7441 = / Latitude 7455") Reported-by: Rafael Dettogni Guariento Tested-by: Rafael Dettogni Guariento Signed-off-by: Avalon Vargas --- Equivalent configurations have been tested on two Dell Inspiron 7441 units. Rafael tested this patch's resulting nodes on his stock DTB, verified the live interpolated table, and confirmed brightness control, Fn keys, no low-brightness flicker, and successful suspend/resume. His Tested-by was supplied by direct email. The 4266537 ns PWM period is borrowed from the upstream ThinkPad T14s LCD configuration. It works on both tested units but has not been measured from Dell firmware. Feedback on that choice is welcome. Validation: strict checkpatch has only the missing public report URL warning for Reported-by (the report was direct email). GCC/dtc DTB build and dt-validate against this tree's bindings pass, with the same dtc warnings as the unchanged base. The kernel dtbs_check target was not run. This is scoped to the 7441. The earlier report of working AUX control on a 7445 with the same panel model remains to be compared for platform, EDID and DPCD differences. --- .../qcom/x1e80100-dell-inspiron-14-plus-7441.dts | 32 ++++++++++++++++++= ++++ 1 file changed, 32 insertions(+) diff --git a/arch/arm64/boot/dts/qcom/x1e80100-dell-inspiron-14-plus-7441.d= ts b/arch/arm64/boot/dts/qcom/x1e80100-dell-inspiron-14-plus-7441.dts index 75e10d97c..98632cccd 100644 --- a/arch/arm64/boot/dts/qcom/x1e80100-dell-inspiron-14-plus-7441.dts +++ b/arch/arm64/boot/dts/qcom/x1e80100-dell-inspiron-14-plus-7441.dts @@ -10,6 +10,19 @@ / { model =3D "Dell Inspiron 14 Plus 7441"; compatible =3D "dell,inspiron-14-plus-7441", "qcom,x1e80100"; + + backlight: backlight { + compatible =3D "pwm-backlight"; + pwms =3D <&pmk8550_pwm 0 4266537>; + power-supply =3D <&vreg_edp_3p3>; + + brightness-levels =3D <0 10 20 30 40 50 60 70 80 90 100>; + num-interpolated-steps =3D <10>; + default-brightness-level =3D <80>; + + pinctrl-0 =3D <&edp_bl_pwm>; + pinctrl-names =3D "default"; + }; }; =20 &sound { @@ -42,6 +55,25 @@ &iris { status =3D "okay"; }; =20 +&mdss_dp3 { + aux-bus { + panel { + backlight =3D <&backlight>; + }; + }; +}; + +&pmk8550_gpios { + edp_bl_pwm: edp-bl-pwm-state { + pins =3D "gpio5"; + function =3D "func3"; + }; +}; + +&pmk8550_pwm { + status =3D "okay"; +}; + &remoteproc_adsp { firmware-name =3D "qcom/x1e80100/dell/inspiron-14-plus-7441/qcadsp8380.mb= n", "qcom/x1e80100/dell/inspiron-14-plus-7441/adsp_dtbs.elf"; --- base-commit: 704340f1cd0dcef829eb62f5b48ae95a2ce17bdf change-id: 20260918-dell7441-backlight-00212af0da18 Best regards, -- =20 Avalon Vargas