From nobody Fri Sep 25 09:26:29 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 5D903496D4B; Mon, 14 Sep 2026 18:14:18 +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=1789409658; cv=none; b=eN0THxb2FyTcwhdJfdE1F3L26MLlwdR3ZVEKWYjxJ5Skfnt44MVQWqXUBZNaKVD75hAIxbdnNNKAjTNToudjMAsQ7+D5qLNHM3IItOcrhFZNuylNea4ouQ1ci9dI3PwEwtLd9f+QOFD99RJQSOHiXfxvcg/Y1olKFsZTXOuG3uU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789409658; c=relaxed/simple; bh=amXM8PKIKM/ToVfiVB0vQgptloCgyaQyxAlLwhGLl88=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=fVafeeoG089NPFULG9eOuuIYdkHjp3epQw7I5Hp7/7srz63h6hmzAU5lOWcPJjITFAWiWzivKxbJQhDn9Ae4E/lpdrEeWiVnjcsjndsI8OjyBaPlDA9Qtir+SnpA0Tvop8959GeXZwWIBybsIe4YOrD3kNsqkD0WLDWJk2SHHg0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pFKpZpZa; 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="pFKpZpZa" Received: by smtp.kernel.org (Postfix) with ESMTPS id CBF2DC2BCFA; Mon, 14 Sep 2026 18:14:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1789409657; bh=amXM8PKIKM/ToVfiVB0vQgptloCgyaQyxAlLwhGLl88=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=pFKpZpZaEMCFVSX+WdizcaK6/XRKL5FLhRv7yVwmrAPQJgjdiyxUcMDd6M12hkBVk M8iMA5oGAadWM9Lwox4N2kzpnPufMf2VQwKrbedk4Uf2E2316r5PEW4lj39QYWPzbv OpvFlJBQi2r4ryW0xOMw7XxC7Wh6t1cACHKFI1Qshv50fop1akH+LLepmlyqqkzUQ+ iQgQvuRFNGk2sNjgSU06w2v1toeify1owwT21An0muGGqk/cycUwytSPtGKGXj37ty /iqQbtO0+DlhN0lNhMdrbO3DScFvOzaU4XMKobdq19DAxPDF9soiN1NG1cpHqd4rEm 9QDnTCKOdN38A== 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 AB519C88E6F; Mon, 14 Sep 2026 18:14:17 +0000 (UTC) From: David Heidelberg via B4 Relay Date: Mon, 14 Sep 2026 20:14:14 +0200 Subject: [PATCH v3 1/4] backlight: qcom-wled: Fix NULL pointer dereference in PM callbacks 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: <20260914-qcom-wled-backlight-v3-1-d69fe9843841@ixit.cz> References: <20260914-qcom-wled-backlight-v3-0-d69fe9843841@ixit.cz> In-Reply-To: <20260914-qcom-wled-backlight-v3-0-d69fe9843841@ixit.cz> To: Lee Jones , Daniel Thompson , Jingoo Han , Helge Deller , Kiran Gunda , Marco Mattiolo , =?utf-8?q?Barnab=C3=A1s_Cz=C3=A9m=C3=A1n?= Cc: linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, phone-devel@vger.kernel.org, Konrad Dybcio , Joel Selvaraj , David Heidelberg , stable@vger.kernel.org X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1308; i=david@ixit.cz; h=from:subject:message-id; bh=+wgGNECp4AfVjE6eGXUZbwV3oC+I+6OGlHWyUvqiSrU=; b=owEBbQKS/ZANAwAIAWACP8TTSSByAcsmYgBqqDl4wE0G4LCdwH1KOt8U61clGOca51ytgIZld bwFVgJO6baJAjMEAAEIAB0WIQTXegnP7twrvVOnBHRgAj/E00kgcgUCaqg5eAAKCRBgAj/E00kg cq2qD/0aMFIPasz9Dr94KFeN+OxZvH6cPkbIhJIaEwboFgwpvYifAXOdMXNhX1s0b5O+mU4PuAC lnHE89ggJu+ZRaIN2k8qfpie2vfRSND14nbhZh7l5CF9kDvoVDpauI3z70Qy2Nt/7x27gFXL99L Td9b7Mj6mehn0nODie3NarMSA4TgsoPYE71WlSgKTMSScu8uHSa1nAFECYmn+yENhruMdFu/uNy J702QAjh/qVCzq2lstGHcuNdjCoWNSsvxiyAjMddfd9nhET3zF2+feFHDuMZCTSEIxn0/l2sKBP Va6yml3X4HMw1NGv79ALiDs3Sb+kH38WSd8exp5kbWUgImmMz3h3fwrSgD4/fg9hqX9MtNYrrK3 nnVoeFSK8C11dsx3390zveC5DWbETJBr7N8P6BoC126OYiOzQ27ssjeSpTonBIldGk5/gpXBTi5 5uw23oHm7a0MOqlmqDipazRf4RCElQPjsjlE/wVi6MttfVcb4BTELPLtI8Lz1fds0/TyZJECGhU Zti23oUC1n8snGjP/2/kp+eqwlAm/VQAsIKgw5oN3mxT1t4+RYNgeypDN0wb2D/YOlRTA8maspw Qzt7O/FvAOgm4WG5hF6CfRdzUEj9dzKvnhuOdNxWpx4YHg3IbhxD9jjOi1/yPdN5g6TwvV1XSAh wo1dKof/VZRK06A== X-Developer-Key: i=david@ixit.cz; a=openpgp; fpr=D77A09CFEEDC2BBD53A7047460023FC4D3492072 X-Endpoint-Received: by B4 Relay for david@ixit.cz/default with auth_id=355 X-Original-From: David Heidelberg Reply-To: david@ixit.cz From: David Heidelberg wled_probe() doesn't set the driver data for the platform device. As a result, dev_get_drvdata() in wled_remove() will return NULL, leading to a NULL pointer dereference afterward. Set the platform device driver data in wled_probe(). Cc: stable@vger.kernel.org Fixes: feeab87b3072 ("backlight: qcom-wled: Add support for short circuit h= andling") Signed-off-by: David Heidelberg --- drivers/video/backlight/qcom-wled.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/= qcom-wled.c index 650dd95f06ef5..a76158a298335 100644 --- a/drivers/video/backlight/qcom-wled.c +++ b/drivers/video/backlight/qcom-wled.c @@ -1747,16 +1747,17 @@ static int wled_probe(struct platform_device *pdev) =20 memset(&props, 0, sizeof(struct backlight_properties)); props.type =3D BACKLIGHT_RAW; props.brightness =3D val; props.max_brightness =3D wled->max_brightness; bl =3D devm_backlight_device_register(&pdev->dev, wled->name, &pdev->dev, wled, &wled_ops, &props); + platform_set_drvdata(pdev, bl); return PTR_ERR_OR_ZERO(bl); }; =20 static void wled_remove(struct platform_device *pdev) { struct wled *wled =3D platform_get_drvdata(pdev); =20 mutex_destroy(&wled->lock); --=20 2.55.0 From nobody Fri Sep 25 09:26:29 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 5D75735AC03; 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charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260914-qcom-wled-backlight-v3-2-d69fe9843841@ixit.cz> References: <20260914-qcom-wled-backlight-v3-0-d69fe9843841@ixit.cz> In-Reply-To: <20260914-qcom-wled-backlight-v3-0-d69fe9843841@ixit.cz> To: Lee Jones , Daniel Thompson , Jingoo Han , Helge Deller , Kiran Gunda , Marco Mattiolo , =?utf-8?q?Barnab=C3=A1s_Cz=C3=A9m=C3=A1n?= Cc: linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, phone-devel@vger.kernel.org, Konrad Dybcio , Joel Selvaraj , David Heidelberg , stable@vger.kernel.org X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1777; i=david@ixit.cz; h=from:subject:message-id; bh=l2V9M/mtqxNb2sIjHPyjkihrWhmivYuqBuqKZxlIoYM=; b=owEBbQKS/ZANAwAIAWACP8TTSSByAcsmYgBqqDl4e+EJzY/iCyxKxGF4mhW9oay6H5NgaCsGd Ohbw0JWgXWJAjMEAAEIAB0WIQTXegnP7twrvVOnBHRgAj/E00kgcgUCaqg5eAAKCRBgAj/E00kg cmttD/4g8nziAhjgPhmtm3FoI3IvdN4iwbPG/MHGtdHuGY5A/UGENs944vkL0FDaObco14X87RS PWvcnas3xWcFqqi8SRIq9W3VjCmY1lYTKC/iMA7voLvBveHndyxNbuAwsEeg/52HbWMhJqzcHSu jI+F0WILo1resu1sMN6JWtDEdPGTbVFApxVG5lvDSvpivqMu4qFiC/VCqm7k+jJNd0HJIyixPyB 9s5tOcOHL7+tlsY7Mi3Y+1fodLRVB537xn7+wOiKErHPPjL5g4/sMH9+go7L7F+yt37vrelpF4W JsoawBydmLnDQf387r/558axlGsDKfX3K/eZ5m7ZlqimE5VOqMhAJcoBNWy9w/qhAWvkxDL3y26 uVatY0mKQEXnhWoAbpGL4TzEV48jGejbg/ynxt/VVCCKKPguiUyxVjDiK1Fgn/joxyyKi204XqR s1MXMSYiG/VuB4HpBmKEYiox8Wuk7Y6sFvvi/3cAqCyxAL5SOnhV+PY2g0iMLvjgd8UsvJS8fCJ cP6Nl0yvvTBfltTML1LGX/YHPu58+kdXUbD+49NgFG7KcFtU0MsD0UzkkKyBqRQqgkmmb7laDqh IXKneKRRpqvmLmSWum0wYBlOogDmy36YxZQdAIcepMkFPJ4rwRDb/HGk8NHSesqLk8pHIbmspMC X+UMNFwk1DlrFVQ== X-Developer-Key: i=david@ixit.cz; a=openpgp; fpr=D77A09CFEEDC2BBD53A7047460023FC4D3492072 X-Endpoint-Received: by B4 Relay for david@ixit.cz/default with auth_id=355 X-Original-From: David Heidelberg Reply-To: david@ixit.cz From: David Heidelberg WLED3 has a 16-bit brightness register pair per string, at 0x40 + 2*n, which is what the pm8941-wled driver wrote to: rc =3D regmap_bulk_write(wled->regmap, wled->addr + WLED3_CTRL_REG_VAL_BASE + 2 * i, v, 2); The restructuring for WLED3 turned that into WLED3_SINK_REG_BRIGHT(n), defined as 0x40 + n, so the two byte writes for consecutive strings overlap: string 1 overwrites the MSB of string 0 with its own LSB, and with the default three strings only string 1 ends up with the requested value. Use the 2 byte stride. Fixes: 775d2ffb4af6 ("backlight: qcom-wled: Restructure the driver for WLED= 3") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: David Heidelberg --- drivers/video/backlight/qcom-wled.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/= qcom-wled.c index a76158a298335..e1962c2d90ed4 100644 --- a/drivers/video/backlight/qcom-wled.c +++ b/drivers/video/backlight/qcom-wled.c @@ -54,17 +54,17 @@ #define WLED3_SINK_REG_SYNC 0x47 #define WLED3_SINK_REG_SYNC_CLEAR 0x00 =20 #define WLED3_SINK_REG_CURR_SINK 0x4f #define WLED3_SINK_REG_CURR_SINK_MASK GENMASK(7, 5) #define WLED3_SINK_REG_CURR_SINK_SHFT 5 =20 /* WLED3 specific per-'string' registers below */ -#define WLED3_SINK_REG_BRIGHT(n) (0x40 + n) +#define WLED3_SINK_REG_BRIGHT(n) (0x40 + (n * 0x10)) =20 #define WLED3_SINK_REG_STR_MOD_EN(n) (0x60 + (n * 0x10)) #define WLED3_SINK_REG_STR_MOD_MASK BIT(7) =20 #define WLED3_SINK_REG_STR_FULL_SCALE_CURR(n) (0x62 + (n * 0x10)) #define WLED3_SINK_REG_STR_FULL_SCALE_CURR_MASK GENMASK(4, 0) =20 #define WLED3_SINK_REG_STR_MOD_SRC(n) (0x63 + (n * 0x10)) --=20 2.55.0 From nobody Fri Sep 25 09:26:29 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 6E9A149B5B5; 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charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260914-qcom-wled-backlight-v3-3-d69fe9843841@ixit.cz> References: <20260914-qcom-wled-backlight-v3-0-d69fe9843841@ixit.cz> In-Reply-To: <20260914-qcom-wled-backlight-v3-0-d69fe9843841@ixit.cz> To: Lee Jones , Daniel Thompson , Jingoo Han , Helge Deller , Kiran Gunda , Marco Mattiolo , =?utf-8?q?Barnab=C3=A1s_Cz=C3=A9m=C3=A1n?= Cc: linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, phone-devel@vger.kernel.org, Konrad Dybcio , Joel Selvaraj , David Heidelberg , stable@vger.kernel.org X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=6061; i=david@ixit.cz; h=from:subject:message-id; bh=3WGdcvqOUloaYBLTk1YaA0eDYI6mzCc0WNIO53NRWmA=; b=owEBbQKS/ZANAwAIAWACP8TTSSByAcsmYgBqqDl4GQbuShgbe3QqPkOyetZoUFtqy74y+hFLK XFqNT1EDTGJAjMEAAEIAB0WIQTXegnP7twrvVOnBHRgAj/E00kgcgUCaqg5eAAKCRBgAj/E00kg cg7KD/9kY2hkrplkQqZLwDCFWID08FdixchXkdo/zTjJ1OLYjkM7iSIaCdMb0tzoC/CEz5BArdi QMwNCTvf/c1+qF8K103ud+rx0o1kORX6JsZSxaHW4y8hzjyec7Vn+5qHfVDaBjEDuRqLHzAHgqj 5PIdZrs4x2FRQPziwdd9A485v2Zf89MSFTS/roINZZfoC9xereEkpwBedKl8bfCi/tp0vXxWe8Q uh9cZJFPZ6FgoCMBF7bZRJ2YCIByCarpUvWCYpAsfgbcsgJyJwgKn+yh1B7LV/y/zY1Dlhp/vQP kMx/cJPM11ezM222JWfW+KNVDsMkKZpeyiLoPzaDvgfc5qUCVlg9AyVfOr7gfCnsLQOHvCXtlyJ mCyV6A1sH/sENM5+cczel/fnbWlArX3R86bsa1nietd+rauvNAGAL/9v592pOVgGB0KlfuFCn6N TbcUwL5zW+vt4O1sXtjCcVICFscL5egf1O7ceXova3x+8+Ufe52k6a1+gQdKkHjWP0PnuwFCUlx Ij1RNrjjc7qff6MksUbfNUe8Ji9gEyIg4VYH7FTBA5DGD3o3Q3y0znIqdFauBORNjcb6Iv5kDmV s77gs3zGbx64+yWB1MkVeG0BtObv9MW5m8SRItxq+NB9pUABT7PngBS8OgHGNeE/9YABu6/O68x A98fyuoDu+hJb9Q== X-Developer-Key: i=david@ixit.cz; a=openpgp; fpr=D77A09CFEEDC2BBD53A7047460023FC4D3492072 X-Endpoint-Received: by B4 Relay for david@ixit.cz/default with auth_id=355 X-Original-From: David Heidelberg Reply-To: david@ixit.cz From: David Heidelberg wled_configure_ovp_irq() derives the initial state of the OVP interrupt from the hardware: /* Keep OVP irq disabled until module is enabled */ if (!(val & WLED3_CTRL_REG_MOD_EN_MASK)) disable_irq(wled->ovp_irq); but wled->brightness, which is what the rest of the driver uses to tell whether the module is on, is left at zero. On boards where the bootloader hands the kernel a lit backlight the two disagree. MOD_EN is already set, so the interrupt is left enabled, while wled_update_status() still believes the backlight is off and takes if (!!brightness !=3D !!wled->brightness) rc =3D wled_module_enable(wled, !!brightness); on the first backlight update. wled_module_enable() then schedules wled_ovp_work(), which calls enable_irq() on the already enabled interrupt: Unbalanced enable for IRQ 176 WARNING: CPU: 0 PID: 160 at kernel/irq/manage.c:774 __enable_irq+0x50/0x80 Hardware name: Xiaomi Pocophone F1 (DT) Workqueue: events wled_ovp_work Call trace: __enable_irq+0x50/0x80 enable_irq+0x48/0xa0 wled_ovp_work+0x18/0x24 process_one_work+0x1d0/0x350 worker_thread+0x13c/0x460 kthread+0x110/0x114 ret_from_fork+0x10/0x20 The bootloader is not the only way to get there. The readback runs after wledN_setup(), and wled4_setup() sets MOD_EN itself on the path where the sink configuration does not already match, as does the tail of wled_auto_string_detection(), which all three setup paths can reach through wled_auto_detection_at_init(). A cold-booted board with a dark panel can therefore reach the same disagreement. Move the MOD_EN readback into wled_probe() and use it to seed wled->brightness, so the driver starts out agreeing with the hardware, and key the OVP interrupt off wled->brightness instead. The first backlight update then only reprograms the brightness registers and leaves both the module and the interrupt alone. The OVP interrupt also stays armed from probe whenever the module is already enabled, rather than being disabled at probe and only enabled once something writes brightness. Note that a backlight update requesting brightness 0 before any non-zero one now really does turn the module off wherever MOD_EN was already set, where before it was silently ignored. wled->brightness is seeded with default-brightness rather than the level the bootloader actually programmed, so the first update can still step the brightness. Reading that level back is version specific and is done in a follow-up, to keep this fix small enough to backport. Assisted-by: LLM Fixes: 8663c188beea ("backlight: qcom-wled: Add auto string detection logic= ") Cc: stable@vger.kernel.org Signed-off-by: David Heidelberg --- drivers/video/backlight/qcom-wled.c | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-) diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/= qcom-wled.c index e1962c2d90ed4..eb742a6598173 100644 --- a/drivers/video/backlight/qcom-wled.c +++ b/drivers/video/backlight/qcom-wled.c @@ -1622,54 +1622,49 @@ static int wled_configure_short_irq(struct wled *wl= ed, =20 return rc; } =20 static int wled_configure_ovp_irq(struct wled *wled, struct platform_device *pdev) { int rc; - u32 val; =20 wled->ovp_irq =3D platform_get_irq_byname(pdev, "ovp"); if (wled->ovp_irq < 0) { dev_dbg(&pdev->dev, "OVP IRQ not found - disabling automatic string dete= ction\n"); return 0; } =20 rc =3D devm_request_threaded_irq(wled->dev, wled->ovp_irq, NULL, wled_ovp_irq_handler, IRQF_ONESHOT, "wled_ovp_irq", wled); if (rc < 0) { wled->ovp_irq =3D 0; return 0; } =20 - rc =3D regmap_read(wled->regmap, wled->ctrl_addr + - WLED3_CTRL_REG_MOD_EN, &val); - if (rc < 0) - return rc; - - /* Keep OVP irq disabled until module is enabled */ - if (!(val & WLED3_CTRL_REG_MOD_EN_MASK)) + /* Keep the OVP irq disabled until the module is enabled */ + if (!wled->brightness) disable_irq(wled->ovp_irq); =20 return 0; } =20 static const struct backlight_ops wled_ops =3D { .update_status =3D wled_update_status, }; =20 static int wled_probe(struct platform_device *pdev) { struct backlight_properties props; struct backlight_device *bl; struct wled *wled; struct regmap *regmap; + u32 mod_en; u32 val; int rc; =20 regmap =3D dev_get_regmap(pdev->dev.parent, NULL); if (!regmap) { dev_err(&pdev->dev, "Unable to get regmap\n"); return -EINVAL; } @@ -1729,27 +1724,42 @@ static int wled_probe(struct platform_device *pdev) =20 default: dev_err(wled->dev, "Invalid WLED version\n"); break; } =20 INIT_DELAYED_WORK(&wled->ovp_work, wled_ovp_work); =20 + val =3D WLED_DEFAULT_BRIGHTNESS; + of_property_read_u32(pdev->dev.of_node, "default-brightness", &val); + + /* + * The module may already be enabled, either by a bootloader that left + * the backlight lit or by the setup above. Record that, so that the + * first brightness update does not enable an already enabled module, + * and so that the OVP irq is armed from probe rather than from that + * first update. + */ + rc =3D regmap_read(wled->regmap, wled->ctrl_addr + WLED3_CTRL_REG_MOD_EN, + &mod_en); + if (rc < 0) + return rc; + + if (mod_en & WLED3_CTRL_REG_MOD_EN_MASK) + wled->brightness =3D val; + rc =3D wled_configure_short_irq(wled, pdev); if (rc < 0) return rc; =20 rc =3D wled_configure_ovp_irq(wled, pdev); if (rc < 0) return rc; =20 - val =3D WLED_DEFAULT_BRIGHTNESS; - of_property_read_u32(pdev->dev.of_node, "default-brightness", &val); - memset(&props, 0, sizeof(struct backlight_properties)); props.type =3D BACKLIGHT_RAW; props.brightness =3D val; props.max_brightness =3D wled->max_brightness; bl =3D devm_backlight_device_register(&pdev->dev, wled->name, &pdev->dev, wled, &wled_ops, &props); platform_set_drvdata(pdev, bl); --=20 2.55.0 From nobody Fri Sep 25 09:26:29 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 6E0F4499F14; 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charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260914-qcom-wled-backlight-v3-4-d69fe9843841@ixit.cz> References: <20260914-qcom-wled-backlight-v3-0-d69fe9843841@ixit.cz> In-Reply-To: <20260914-qcom-wled-backlight-v3-0-d69fe9843841@ixit.cz> To: Lee Jones , Daniel Thompson , Jingoo Han , Helge Deller , Kiran Gunda , Marco Mattiolo , =?utf-8?q?Barnab=C3=A1s_Cz=C3=A9m=C3=A1n?= Cc: linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, phone-devel@vger.kernel.org, Konrad Dybcio , Joel Selvaraj , David Heidelberg X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=6845; i=david@ixit.cz; h=from:subject:message-id; bh=Nidh9qw4K//eY6dG1HyoeNGnuAFJH6nbVwPXrtUb50U=; b=owEBbQKS/ZANAwAIAWACP8TTSSByAcsmYgBqqDl4V+pJrmV2561jKJU01TGxU8vgcqrIh5X2a PlsSuXv6ESJAjMEAAEIAB0WIQTXegnP7twrvVOnBHRgAj/E00kgcgUCaqg5eAAKCRBgAj/E00kg ckUyD/4kelPr0O/PIMcfSR+A8dfZvlicHAnRvsnN+cmtuK0OC3QRHLcyZnmSMxYm52OmlJ9g6Bo clOpYrBCRKVkkwqPYtRFTwb76dByJqUHR8uSPhY6YQpWXdLxJqM73lHsgCDC52dxoFs5Vv3DZC8 RvdzYWpI6rDCsQ5vQIWPXWfkLe7z0cORtgAUXYW7ZFV4vHMKXZJy9owHFFcDLMDpHZx6IRM/r/g 3T5vTeFsGj8kX0DgRjBMFiwX6NnYyGCiXCrJ9Jq2/+Vf5ovJv0qcJJvthTagR6Gqs9NswdJI8WL bNoG2P/5Z87z5Lk+DojHqExxLYHnL7S+BNSRrfPmiA1cS/8SXyOgiIW6X2lEjdCxmKVnsb0aF7E YX1RNRn6fmo8ZihYxi6oH17H+fwmq1tE5Dv4Agg3DxDKlOjHhcM1LQ0DQESZOeo126EZBiFqSFx BsKhQy5mew9AMTiDiliXS2mKzwZaVuZqj2HYSuAbgrMuffuL21bvV2ShwAGVexqCgKvgwKbQ7M/ svmTCV+tgboZauA8PxBt6wu6HRfenR11R/RL2f8QK/GW0O5G7zmjCWbsfjIyOXV9RYHjXyc6sOV 3knegkXTvUi1fdGjMaE7wYTKPn3jgWgiLA/9/bQRLfk9HhXQouMTUbrUmSym6c3tbrkZMb/DrnB 7+0Ax2FRYsLpz3w== X-Developer-Key: i=david@ixit.cz; a=openpgp; fpr=D77A09CFEEDC2BBD53A7047460023FC4D3492072 X-Endpoint-Received: by B4 Relay for david@ixit.cz/default with auth_id=355 X-Original-From: David Heidelberg Reply-To: david@ixit.cz From: David Heidelberg Since the previous change wled_probe() seeds wled->brightness from MOD_EN, but with default-brightness rather than the level the hardware is actually driving, so a backlight left lit by the bootloader still visibly steps on the first update, and actual_brightness reports the last value written rather than what the panel shows. Add wled_read_brightness(), which returns 0 when MOD_EN is clear and otherwise reads the brightness register the matching wledN_set_brightness() writes: the first enabled string on WLED3 and WLED4, the selected modulator on WLED5. Use it to seed both wled->brightness and the initial backlight property, and expose it as backlight_ops.get_brightness so that actual_brightness reflects the hardware too. A module that is enabled with the brightness registers at zero, which wled4_setup() and wled_auto_string_detection() can leave behind on a cold boot, now reads back as off. The OVP interrupt is then armed by the first brightness update rather than from probe, which is what happens on every other board where the module starts out disabled. Suggested-by: Konrad Dybcio Assisted-by: LLM Signed-off-by: David Heidelberg --- drivers/video/backlight/qcom-wled.c | 76 +++++++++++++++++++++++++++++++--= ---- 1 file changed, 64 insertions(+), 12 deletions(-) diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/= qcom-wled.c index eb742a6598173..471a0cb2b81f6 100644 --- a/drivers/video/backlight/qcom-wled.c +++ b/drivers/video/backlight/qcom-wled.c @@ -54,17 +54,17 @@ #define WLED3_SINK_REG_SYNC 0x47 #define WLED3_SINK_REG_SYNC_CLEAR 0x00 =20 #define WLED3_SINK_REG_CURR_SINK 0x4f #define WLED3_SINK_REG_CURR_SINK_MASK GENMASK(7, 5) #define WLED3_SINK_REG_CURR_SINK_SHFT 5 =20 /* WLED3 specific per-'string' registers below */ -#define WLED3_SINK_REG_BRIGHT(n) (0x40 + (n * 0x10)) +#define WLED3_SINK_REG_BRIGHT(n) (0x40 + (n * 0x2)) =20 #define WLED3_SINK_REG_STR_MOD_EN(n) (0x60 + (n * 0x10)) #define WLED3_SINK_REG_STR_MOD_MASK BIT(7) =20 #define WLED3_SINK_REG_STR_FULL_SCALE_CURR(n) (0x62 + (n * 0x10)) #define WLED3_SINK_REG_STR_FULL_SCALE_CURR_MASK GENMASK(4, 0) =20 #define WLED3_SINK_REG_STR_MOD_SRC(n) (0x63 + (n * 0x10)) @@ -285,16 +285,60 @@ static int wled5_set_brightness(struct wled *wled, u1= 6 brightness) WLED5_SINK_REG_MOD_A_BRIGHTNESS_LSB : WLED5_SINK_REG_MOD_B_BRIGHTNESS_LSB; =20 rc =3D regmap_bulk_write(wled->regmap, wled->sink_addr + offset, &v, sizeof(v)); return rc; } =20 +static int wled_read_brightness(struct wled *wled) +{ + u16 addr, mask; + __le16 v; + u32 val; + int rc; + + rc =3D regmap_read(wled->regmap, wled->ctrl_addr + WLED3_CTRL_REG_MOD_EN, + &val); + if (rc < 0) + return rc; + + if (!(val & WLED3_CTRL_REG_MOD_EN_MASK)) + return 0; + + switch (wled->version) { + case 3: + addr =3D wled->sink_addr + + WLED3_SINK_REG_BRIGHT(wled->cfg.enabled_strings[0]); + mask =3D WLED3_SINK_REG_BRIGHT_MAX; + break; + case 4: + addr =3D wled->sink_addr + + WLED4_SINK_REG_BRIGHT(wled->cfg.enabled_strings[0]); + mask =3D WLED3_SINK_REG_BRIGHT_MAX; + break; + case 5: + addr =3D wled->sink_addr + (wled->cfg.mod_sel =3D=3D MOD_A ? + WLED5_SINK_REG_MOD_A_BRIGHTNESS_LSB : + WLED5_SINK_REG_MOD_B_BRIGHTNESS_LSB); + mask =3D WLED5_SINK_REG_BRIGHT_MAX_15B; + break; + default: + dev_err(wled->dev, "Invalid WLED version\n"); + return -EINVAL; + } + + rc =3D regmap_bulk_read(wled->regmap, addr, &v, sizeof(v)); + if (rc < 0) + return rc; + + return min_t(u32, le16_to_cpu(v) & mask, wled->max_brightness); +} + static void wled_ovp_work(struct work_struct *work) { struct wled *wled =3D container_of(work, struct wled, ovp_work.work); enable_irq(wled->ovp_irq); } =20 static int wled_module_enable(struct wled *wled, int val) @@ -475,16 +519,28 @@ static int wled_update_status(struct backlight_device= *bl) wled->brightness =3D brightness; =20 unlock_mutex: mutex_unlock(&wled->lock); =20 return rc; } =20 +static int wled_get_brightness(struct backlight_device *bl) +{ + struct wled *wled =3D bl_get_data(bl); + int rc; + + mutex_lock(&wled->lock); + rc =3D wled_read_brightness(wled); + mutex_unlock(&wled->lock); + + return rc; +} + static int wled4_cabc_config(struct wled *wled, bool enable) { int i, j, rc; u8 val; =20 for (i =3D 0; i < wled->cfg.num_strings; i++) { j =3D wled->cfg.enabled_strings[i]; =20 @@ -1646,25 +1702,25 @@ static int wled_configure_ovp_irq(struct wled *wled, if (!wled->brightness) disable_irq(wled->ovp_irq); =20 return 0; } =20 static const struct backlight_ops wled_ops =3D { .update_status =3D wled_update_status, + .get_brightness =3D wled_get_brightness, }; =20 static int wled_probe(struct platform_device *pdev) { struct backlight_properties props; struct backlight_device *bl; struct wled *wled; struct regmap *regmap; - u32 mod_en; u32 val; int rc; =20 regmap =3D dev_get_regmap(pdev->dev.parent, NULL); if (!regmap) { dev_err(&pdev->dev, "Unable to get regmap\n"); return -EINVAL; } @@ -1728,41 +1784,37 @@ static int wled_probe(struct platform_device *pdev) } =20 INIT_DELAYED_WORK(&wled->ovp_work, wled_ovp_work); =20 val =3D WLED_DEFAULT_BRIGHTNESS; of_property_read_u32(pdev->dev.of_node, "default-brightness", &val); =20 /* - * The module may already be enabled, either by a bootloader that left - * the backlight lit or by the setup above. Record that, so that the - * first brightness update does not enable an already enabled module, - * and so that the OVP irq is armed from probe rather than from that - * first update. + * The module may already be lit, either by the bootloader or by the + * setup above. Start from what the hardware is driving, so that the + * first brightness update does not step the brightness. */ - rc =3D regmap_read(wled->regmap, wled->ctrl_addr + WLED3_CTRL_REG_MOD_EN, - &mod_en); + rc =3D wled_read_brightness(wled); if (rc < 0) return rc; =20 - if (mod_en & WLED3_CTRL_REG_MOD_EN_MASK) - wled->brightness =3D val; + wled->brightness =3D rc; =20 rc =3D wled_configure_short_irq(wled, pdev); if (rc < 0) return rc; =20 rc =3D wled_configure_ovp_irq(wled, pdev); if (rc < 0) return rc; =20 memset(&props, 0, sizeof(struct backlight_properties)); props.type =3D BACKLIGHT_RAW; - props.brightness =3D val; + props.brightness =3D wled->brightness ?: val; props.max_brightness =3D wled->max_brightness; bl =3D devm_backlight_device_register(&pdev->dev, wled->name, &pdev->dev, wled, &wled_ops, &props); platform_set_drvdata(pdev, bl); return PTR_ERR_OR_ZERO(bl); }; =20 --=20 2.55.0