From mboxrd@z Thu Jan 1 00:00:00 1970 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 E757F381B05; Tue, 8 Sep 2026 20:53:52 +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=1788900833; cv=none; b=oUKdsTqECECYHB7aQZc264n46r1Hjwfa3lRtGGUGIGlzFWcc7BcAihBMj+zLPsmsxgEvW6gmEWSAwz5/sbbAf3FRpdgFaMS4agt6pUuM4MlWFYDxCcnSym/NL+5tRy17XGUm51Nrh5MIs8NC1lLcH5NMFGv+Ec/sC+XxKb+Z1Pw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788900833; c=relaxed/simple; bh=9ydGklz8bZHOpqIknHpNgAna7Etxuu7JUtYpdMotKqE=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=rGlkFcgXNn5KzYcK5vmyWVr9pvug7OJ3n3hVS35UJEcKQ52v6vncojSCKKqkhem3yGC5LYAu0haWuII9UyVHWHK/zmIIZT34hUMJ1iNfqALHOA5RMWJ53inbt1/haGnSXlHabMNFabP5QjmVXdH6TS/CTe7RykXaDIRXmythiZE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MUBUX+Od; 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="MUBUX+Od" Received: by smtp.kernel.org (Postfix) with ESMTPS id 502E8C2BCB8; Tue, 8 Sep 2026 20:53:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1788900832; bh=9ydGklz8bZHOpqIknHpNgAna7Etxuu7JUtYpdMotKqE=; h=From:Date:Subject:To:Cc:Reply-To:From; b=MUBUX+OdC6MdOoyat4SfIhsk/mYkz4s59QX5MjXRe2hVpWVeJ381rg3owK6oNbOCo lUgR2Qs/oUYIm01oYYv3pUM+/u9SXoV8CMBvQrIr2qHTXie/VUP27aKbQv/wtCqHnf BRk5aqt8t2RJ2WWR3NVFtBx0lxDkTWQmHGmUAYdr50BtU5K4g3P92UIav2P6/Tu6iQ uvcezXgqwcb5r1UdX3UlPVUt++cyYYegCEZAYiRf2MPNfr2lsjrEMGv0CDMtTIpnkB iS137AuY68j1uaP/Ll00PU2sSut/z2yLy4jfQe0YF3NgB9qG5BgC1B4nO3DTtatBqh gUqU0HZytNieg== 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 2FE48C79FAA; Tue, 8 Sep 2026 20:53:52 +0000 (UTC) From: David Heidelberg via B4 Relay Date: Tue, 08 Sep 2026 22:53:47 +0200 Subject: [PATCH] backlight: qcom-wled: Fix unbalanced OVP IRQ enable at probe Precedence: bulk X-Mailing-List: linux-fbdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260908-qcom-wled-backlight-v1-1-c4dd4eabda07@ixit.cz> X-B4-Tracking: v=1; b=H4sIAAAAAAAC/yXMSQ6DMAxA0asgr2spDVPpVRALSAyYUoaESULcn QDLt/h/B0uGycLX28HQwpb7zuH98kDVeVcRsnYGKWQkEvHBUfV/XFvSWOTq13JVT1jqJIwDIWM /9MGVg6GSt/uaZo/tXDSkpmsFx3ECFD8JCncAAAA= X-Change-ID: 20260908-qcom-wled-backlight-fd9574027353 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, stable@vger.kernel.org, David Heidelberg X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=6457; i=david@ixit.cz; h=from:subject:message-id; bh=yBiYmO8d6SvubGxXelZ3t3PQpKGgRFigdJU1itdaGJI=; b=owEBbQKS/ZANAwAIAWACP8TTSSByAcsmYgBqoHXe926RXgnO3S+glWPVaG88ro/W9WLSTAOOa RVPKlHctlSJAjMEAAEIAB0WIQTXegnP7twrvVOnBHRgAj/E00kgcgUCaqB13gAKCRBgAj/E00kg cpJiD/98Rs8zIQxocR0idSCh6Ogmgd/J9rMxS2zgWMK/zQLttQS/ry88pN69AVygf/93I4oNLXT HOB/m1kb0y4/vP04Ienuwm5+EbyozXYR6U1IKI475fEIlf+W/Jx3ajQN+wNw/h34kM6syjK0ceq ZWSxCkvl4y6seLqWv0lKPk/wJNudf0fbnUgXQ6wyooL9i7KE8SkFLKpcx/U7+VSmJbm5wAloaam cBR3qw/Eos3TXqHer9+V9BYwpRhnG/MKWFx3k5GpNAc3kYdZxEoSGVFH+CZAC1mT6+soAIZXRLd Kt1lAgvuVps7P8XY/dtqDFRAXe4HZb9OO/dElfUmuBbUDveVZpo5w3QiPMufOhCGgvXQZV5f4pN rKrQBqoriJrTSefr34riwr8EKBVmXUDIM2vCPJUGpkp6RJThGtK5+qyGSJ2HGg8Ol6kHdzi3M/N FJ8pCz6dV09pOGUASI5AmctCOb/wX17gf5rDiy6I2HYqe3j0NcxGYxl5NbNMwTT16KqzA6ZG6Ap NqzBPVcmY2zIJ5MbjnITAvToNfbkGQIL8jK0DpJw7ePlzdoBcrUHP9IZDXI80kpa0RV1VINV3M+ IOiJmgxpKkR0z38200Q80msIDnmBFhfnd/6aP7d9a9HJG44syQg15ObqUKjU7aSFwWL3ZQkH/jT adohQTBb5LbvUuQ== 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 != !!wled->brightness) rc = 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 needs a per-version accessor and is left for later. Assisted-by: LLM Fixes: 8663c188beea ("backlight: qcom-wled: Add auto string detection logic") Cc: stable@vger.kernel.org Signed-off-by: David Heidelberg --- this is slightly annoying bug sdm845-mainline had patched for a years, but not very well. This should be the proper patch, got ack from people with Xiaomi Poco F1 (ebbg variant) which does use this so it works. Adding MSM8953 folks into Cc too, which use the early fix. --- 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 650dd95f06ef5..344b8cad90105 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 *wled, return rc; } static int wled_configure_ovp_irq(struct wled *wled, struct platform_device *pdev) { int rc; - u32 val; wled->ovp_irq = platform_get_irq_byname(pdev, "ovp"); if (wled->ovp_irq < 0) { dev_dbg(&pdev->dev, "OVP IRQ not found - disabling automatic string detection\n"); return 0; } rc = 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 = 0; return 0; } - rc = 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); return 0; } static const struct backlight_ops wled_ops = { .update_status = wled_update_status, }; 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; regmap = 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) default: dev_err(wled->dev, "Invalid WLED version\n"); break; } INIT_DELAYED_WORK(&wled->ovp_work, wled_ovp_work); + val = 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 = 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 = val; + rc = wled_configure_short_irq(wled, pdev); if (rc < 0) return rc; rc = wled_configure_ovp_irq(wled, pdev); if (rc < 0) return rc; - val = WLED_DEFAULT_BRIGHTNESS; - of_property_read_u32(pdev->dev.of_node, "default-brightness", &val); - memset(&props, 0, sizeof(struct backlight_properties)); props.type = BACKLIGHT_RAW; props.brightness = val; props.max_brightness = wled->max_brightness; bl = devm_backlight_device_register(&pdev->dev, wled->name, &pdev->dev, wled, &wled_ops, &props); return PTR_ERR_OR_ZERO(bl); --- base-commit: 944a035ecca915ae947905dcfb03f2b9dc6d032c change-id: 20260908-qcom-wled-backlight-fd9574027353 Best regards, -- David Heidelberg