From nobody Thu Sep 24 20:03:33 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 E07EC47FAFB; Mon, 21 Sep 2026 10:46:25 +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=1789987586; cv=none; b=L1Y29wfM73jQy+1IE7Z9SLsEA0Gi6mnnymI3BaOvDmbmTYSsxiquKJ0lEQmDW/WrwsuLzmjcSPMhVYwAJCpZWINcWFDiB+1eBrP4Rg545rSKxt4uzLGSDZF+75tLakb1WdI1tYacZr58+e+uveKU7atCx8EpeiXqDbPH5jbrQrc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789987586; c=relaxed/simple; bh=xN+UJbgsVFesEQgRsqdbzmzNFifNC0e3F6BbeYRcHRo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=FwBLdAoryJllGRu6nky6INoaJ3djHJdOE/H9SBysGO/v3pT9/3engNq9fEVaUC/2J1zS0XrlJYlvzHz7IunwtIzbwX/GvgknXUCymHKPA27y2/nGYyF7tVz2aL02CGc0EH1z12TvlCIrS/WjwC4QYAatDtVjXAh32MxfIBtKh5Y= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QQIBwaew; 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="QQIBwaew" Received: by smtp.kernel.org (Postfix) with ESMTPS id 7C924C2BCB8; Mon, 21 Sep 2026 10:46:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1789987585; bh=xN+UJbgsVFesEQgRsqdbzmzNFifNC0e3F6BbeYRcHRo=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=QQIBwaewbfGLu24MQDGBZJhuZI5r+ZZksRv/HLEWMfxUbtTOTptCi14jk5NcXEDtW VaeT+UWY7g6uVDkncKZVEagOaSVLejPjp1vMuL8JSZ3NxmCl4i7Mw6/ik5JhUwsQJ4 hSYShHiiLu1XhZRCejmaj57ca+bV5muUL5Ri0uJFlYQO+AK/+9jLpgi/L652zPJJPf /v9HoegRKO2L6Ylqw0tag6wE8BFUcSgP77DeXbYA9UZYDZEwNnPje8WqcIHTQrf12+ anlPN8OPeghs4vdmxCe8nJ3UR0MUA8OfrKkaaVp6w6kU3029g90Atu/kKqkVmrlaD9 0WBf8j4XqPjFg== 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 5B728C982E1; Mon, 21 Sep 2026 10:46:25 +0000 (UTC) From: David Heidelberg via B4 Relay Date: Mon, 21 Sep 2026 12:46:22 +0200 Subject: [PATCH v4 1/4] backlight: qcom-wled: Fix NULL pointer dereference in wled_remove() 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: <20260921-qcom-wled-backlight-v4-1-bab8c7ef73cb@ixit.cz> References: <20260921-qcom-wled-backlight-v4-0-bab8c7ef73cb@ixit.cz> In-Reply-To: <20260921-qcom-wled-backlight-v4-0-bab8c7ef73cb@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=1208; i=david@ixit.cz; h=from:subject:message-id; bh=+dZaRJRtQ4v3SzBsEJavUDVtILbeFcbE2ljB22hvcJI=; b=owEBbQKS/ZANAwAIAWACP8TTSSByAcsmYgBqsQr/4lkhyZPqySJGz8AbmEdnqgIJmewQv2Vg8 UJPRD7QvBSJAjMEAAEIAB0WIQTXegnP7twrvVOnBHRgAj/E00kgcgUCarEK/wAKCRBgAj/E00kg cqdgEACW4JkRf6Isv9QBPQ23EC6GzduH57OWTfvtjLxLPCjceEaSPsrzUHJT9Oy2U5NYJwlZ8Ih LbTJS2rNlynQzdPCbqcJEIIwu5KUKLVPJykGUsxclL6gdFXEhcdec7YLRrKMyY6TqxkW6v/cHXQ R4EMHQ9SMCh49+sJE7LdtcZ+y+Z0hqL0XXZuaaXYbj2crc39hI4uxtbuf4gNzIAZm6UW/uDEWma 2fojatxwgf+iXwVUxRyisb70+zwk/L4yR0JHZIUb3+F0+HqwAHbRA2aqMq5stkwWFH1STmscsua /h0FdqK2MtuoFJYpc/sAtq5Okn09o5lqBqqvJQSoHpgjt61KKsBGXMPrUm9LSjmNooroaTeurDB UvJCK3mElpGpDxK5tzkRofhdYjBvfONap1EEYAE3M1Ww3HVqiFECjLj0XtwPR9BGuykdezorZ84 JzCiFjK85ZPU/SduLIumAcsodjnP7py6jwoKN6o4lYfZM3i6z7NIzckd7s1mNyV2y7N1jg3BLru oJKifmcvVRtdOYwAuigCfxdAeetAvoV4rZL1EuvQyhac1cgkDjwyDKMBbdKf/M8SIxdv+c56Js0 b4gfr9vDcu10RMj0wGw0D42DlblpaR9lF0KEIj9fhuZK2m7DSW1D7okZK2DlmJA6eCF+soNV54o w9bufxI8ObtEL4A== 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, platform_get_drvdata() in wled_remove() will return NULL, and the first dereference of it crashes on unbind. 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 Reviewed-by: Konrad Dybcio --- 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..2281007bdd459 100644 --- a/drivers/video/backlight/qcom-wled.c +++ b/drivers/video/backlight/qcom-wled.c @@ -1675,16 +1675,17 @@ static int wled_probe(struct platform_device *pdev) } =20 wled =3D devm_kzalloc(&pdev->dev, sizeof(*wled), GFP_KERNEL); if (!wled) return -ENOMEM; =20 wled->regmap =3D regmap; wled->dev =3D &pdev->dev; + platform_set_drvdata(pdev, wled); =20 wled->version =3D (uintptr_t)of_device_get_match_data(&pdev->dev); if (!wled->version) { dev_err(&pdev->dev, "Unknown device version\n"); return -ENODEV; } =20 mutex_init(&wled->lock); --=20 2.55.0 From nobody Thu Sep 24 20:03:33 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 E069D47FAEA; 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charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260921-qcom-wled-backlight-v4-2-bab8c7ef73cb@ixit.cz> References: <20260921-qcom-wled-backlight-v4-0-bab8c7ef73cb@ixit.cz> In-Reply-To: <20260921-qcom-wled-backlight-v4-0-bab8c7ef73cb@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=1776; i=david@ixit.cz; h=from:subject:message-id; bh=7dg4sNfoJUcVQTg/pZrE7IUtjXq8Oym1qNiml++xiMI=; b=owEBbQKS/ZANAwAIAWACP8TTSSByAcsmYgBqsQr/sPC+A2M95fdj4NxWG/mcIHavg1o987p1L ijk5700k3GJAjMEAAEIAB0WIQTXegnP7twrvVOnBHRgAj/E00kgcgUCarEK/wAKCRBgAj/E00kg coGhEADMtxTn4ww2WMUJwvEDnnzgSyczCpqyJrexzt3wfJ4e37ctZNxb2pOiekO2LXiWSozjtwM Skk0DtVcB8jWMkIp0vtBnWxsjdApCsjudOgv65lXTY20YVP+4f3yvnbJZEBJaHy3HCimLSA3YO7 r07cgUnIsk4f8TWT2UO40uLxcMZjIEVaGakFHOwKHNeyd978d+x7mC4NAJvLFGILR3jRV73lX5D QshqkGFGd6xVd+/L4KWq9TKzJKK3NoOsxDAnDMDRVrfvOcMOS/13VrMkIVX0OgN8gUrkn1/81xa DOo3/sGebkYyoIYHUGEESJjOdN0cVkSk+jU3iBI6SqFksdCJdxnvRz2k4SS3PheAMqq+4c3dEBT b7G17F9scwl9W0tjKq7Sfsi2aXa2WodI8TfDExIYAzI9hZkKSFSWmOdN9U2gtu2pvEQJHoF7adf l6aWlOj7RFyVXbGDDOWWlZI5noqP2SO1mQk1Y0oV15bm0WJR7g0Ny6US01b00mPtS23pX+vbXpq RsiBQUGr/YCy7LXeBMy8v8DLLwWwU5WzvThn28TSYgfyPLPrTvzUpWMfpwQy1SVQfSujBtYAHLy Cp6T+3LBN9vMio/Ydu0HWPLnLV5E6URxcL4GqWOXlalslWw4Ys6jNYmkRXwr0Z/j47/g640reF3 HiyH8n2VkdXPI3Q== 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 Reviewed-by: Konrad Dybcio --- 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 2281007bdd459..f452d328997ad 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 * 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)) --=20 2.55.0 From nobody Thu Sep 24 20:03:33 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 E075E47FAF8; 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charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260921-qcom-wled-backlight-v4-3-bab8c7ef73cb@ixit.cz> References: <20260921-qcom-wled-backlight-v4-0-bab8c7ef73cb@ixit.cz> In-Reply-To: <20260921-qcom-wled-backlight-v4-0-bab8c7ef73cb@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=6057; i=david@ixit.cz; h=from:subject:message-id; bh=TliZA3ecky6AtA5rDK/WH2uUEPyAHUvMci0Rbzp8QCE=; b=owEBbQKS/ZANAwAIAWACP8TTSSByAcsmYgBqsQr/FB9ERVSpERl+ROohiulY91N8X4NLk4Dbu aZhiikzWrGJAjMEAAEIAB0WIQTXegnP7twrvVOnBHRgAj/E00kgcgUCarEK/wAKCRBgAj/E00kg cijDD/4vUflQ26KeZ87eTLHndmBpJcXy9rzAQpHzgroXahbmi9Z2dgAMdZ3+ZXo9zc6xmgcsPCq xQO0gTUZWWwtEQANjPaWSGjGNP8gB9EwqhNRBFidmaB9+9AnayHxKLfdivLtQM3cE24xaB7fRtF c8OzdYzhVANkUISm08TLj1GGwJk8+f3vefglpObTZRCtzB5opPEbgy+pRiXOZXQ1Zrm+yiTLEg2 gk2vZ2qC/xKD3Pd+L+QoOU4xm3KzNvBAMLUEQFR3OHRCegS7LncwC18bCQvYohOYpcOOprhyhsU rECVDhllkfiQJICeVhuKjnvA2r+m9u5I1jLadeq1UV6i0lQnuP5mQoNpZXXfuLdE01DCQg0TSq9 VFYmKOBhzx+5WuYXArGALjzxnsYPUCxSmfPw0s2HjUDrAOuuxOiGkEnF1ehzZniLDpXg3MHzpxV cQLWxf1YVe2/nFSpmGG+2YWXKq7E2xLl6vOB2ThJjtyDjQ8SUB9S893U/1CKWZnsIGhQbBkUXVF d68Jh1cXw6m6v6t41eQKXK0hZ3Gd33FB/vEb/zAACgl087cXdB6bn1a23iGNNPynQQzJjdTXVb+ obbK8pobuY3zXcEoazvoMgAqqfdxAiwyFXhmu/6jFfwzfnxgvOBb3QcPwWy561ZdQTKzUZpQR83 D+Yijv9rF1OXmFg== 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 f452d328997ad..3ce3bade3b8dd 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; } @@ -1730,27 +1725,42 @@ 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); return PTR_ERR_OR_ZERO(bl); --=20 2.55.0 From nobody Thu Sep 24 20:03:33 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 E04B041F5FC; 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charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260921-qcom-wled-backlight-v4-4-bab8c7ef73cb@ixit.cz> References: <20260921-qcom-wled-backlight-v4-0-bab8c7ef73cb@ixit.cz> In-Reply-To: <20260921-qcom-wled-backlight-v4-0-bab8c7ef73cb@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=6134; i=david@ixit.cz; h=from:subject:message-id; bh=Vd0mK0QtPcwQRIQctDNdJy4/aT9MYS6AbqA9R9Lgs7M=; b=owEBbQKS/ZANAwAIAWACP8TTSSByAcsmYgBqsQr/SPXXhzir5slfNf//B0RQVNzZfsL8bCu40 sNHQe0OfyqJAjMEAAEIAB0WIQTXegnP7twrvVOnBHRgAj/E00kgcgUCarEK/wAKCRBgAj/E00kg cohSD/43ZwcZK12PiDRqLFQ1BSQj/qpvka/d9RpoDqvnRgqK4kf2y0NM4dS2TQK/FdW5WZ+/Yi6 y31aalt+YjK/Bq+IGnkO6rBIQHuRhNA6r3pDZKFVV2t0IG8sYVENY97njnDu2/NTvsBQ3UsSv4j pK9l2rU88hLobLSxO1zzEYAUrApOR/ibpYipJ12A7jwGrVUeJNF5eKYaLAudIO7AZv+B7UUms/h ssYYHA8EeTaukyFUvWw8PDd0KJsuEHa8GqolTOJxdQND6CJdl5Lx0Mlg7jWry/2wZZmtxPMjVBR JBZBXFs+8EeMXM9QapCVLV/aIgVeO+xUcOoQbMyQBMauFfXF0e/YDW/PR7Qhk4SlpHW8TMCvPWg ZYbG23sGon4Qo54P9PNe9IAQuwaHXq3eQJWZxkmfL0ExRhPhas0EUGledpjCjvTuiOOSNBnl4jW E6VPMZpoTLa1X5wUymOunEKw1tq8BWTDaw8Ic0mdjY0UhOahKxEhQ9AhiaJxPa9nouVdKZJnGSt rRS1pntI1oWsfwPcJClyNmXPLt51XZygdR1JLCUo65JPn5rqBWvMQLba4eXLY7xSCSKNToM1/2K BJMD71JkHf15/fCsvsPbv1dPF0z71Z2d1YZZTa5AoRBjjg6sTfUal+29YX7AOYBax7jxN95Hlzv F3B9oCckP7WZJdg== 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 | 74 +++++++++++++++++++++++++++++++--= ---- 1 file changed, 63 insertions(+), 11 deletions(-) diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/= qcom-wled.c index 3ce3bade3b8dd..ca350f320e177 100644 --- a/drivers/video/backlight/qcom-wled.c +++ b/drivers/video/backlight/qcom-wled.c @@ -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; } @@ -1729,41 +1785,37 @@ 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); return PTR_ERR_OR_ZERO(bl); }; =20 static void wled_remove(struct platform_device *pdev) --=20 2.55.0