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 2E77033A712; Fri, 9 Jan 2026 11:58:08 +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=1767959888; cv=none; b=QV23C8sHPR/yhrK/Ny8Ysj3xdPEefMUDreY7Zq/TGPrvhKGBb9ssdCYBFl5NyJKB3Mb7NSFiLH7+qGs59WziKSYKaBuuKQ9cvpjchYGr9enppx96yALhtOM344GgOWCW33+TS39ecT+N9Tqv7kSHwRiOjLndrBC5q+OoEXdMipY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767959888; c=relaxed/simple; bh=j7tbZT8TEuU79UVmRPlPQlktZzGqo/k8abP4bDLS8QI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=uchfZDU632QfoIM1jYzlPtnZq2aZbEbpvPxPz0k0hgOVLz4xfpaTu7lC1iy31ICZMu3k+XweCNa7tcVRpbF0UZvJ7qjw103xIiIkyTxPBcRtxf+N2FPuG2mN7fVeQHBrSemIhTQ9zF5aAsEjn/dUFx2EGAUS9jjgVkTad5XNdLU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=mWAxfvSC; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="mWAxfvSC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF124C4CEF1; Fri, 9 Jan 2026 11:58:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1767959888; bh=j7tbZT8TEuU79UVmRPlPQlktZzGqo/k8abP4bDLS8QI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mWAxfvSCEnxFYPKCOh9tATqOa7RWCDJH9oZYuERqZw/1wufmYC1A5fPfJRnvmkBZV AselIMbeIoIKSXJnOslkHpLVDbSgDvN0JhZloKAIspoVnF1RPxFoy3gKxj0gCllwWB fI3kji/uHoEs3OM3Q/kWzBcA6yuy8E2SIEmNa5w0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Luca Ceresoli , "Daniel Thompson (RISCstar)" , Herve Codina , Alexander Sverdlin , Lee Jones , Sasha Levin Subject: [PATCH 6.6 209/737] backlight: led-bl: Add devlink to supplier LEDs Date: Fri, 9 Jan 2026 12:35:48 +0100 Message-ID: <20260109112141.861259282@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260109112133.973195406@linuxfoundation.org> References: <20260109112133.973195406@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Luca Ceresoli [ Upstream commit 9341d6698f4cfdfc374fb6944158d111ebe16a9d ] LED Backlight is a consumer of one or multiple LED class devices, but devlink is currently unable to create correct supplier-producer links when the supplier is a class device. It creates instead a link where the supplier is the parent of the expected device. One consequence is that removal order is not correctly enforced. Issues happen for example with the following sections in a device tree overlay: // An LED driver chip pca9632@62 { compatible = "nxp,pca9632"; reg = <0x62>; // ... addon_led_pwm: led-pwm@3 { reg = <3>; label = "addon:led:pwm"; }; }; backlight-addon { compatible = "led-backlight"; leds = <&addon_led_pwm>; brightness-levels = <255>; default-brightness-level = <255>; }; In this example, the devlink should be created between the backlight-addon (consumer) and the pca9632@62 (supplier). Instead it is created between the backlight-addon (consumer) and the parent of the pca9632@62, which is typically the I2C bus adapter. On removal of the above overlay, the LED driver can be removed before the backlight device, resulting in: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 ... Call trace: led_put+0xe0/0x140 devm_led_release+0x6c/0x98 Another way to reproduce the bug without any device tree overlays is unbinding the LED class device (pca9632@62) before unbinding the consumer (backlight-addon): echo 11-0062 >/sys/bus/i2c/drivers/leds-pca963x/unbind echo ...backlight-dock >/sys/bus/platform/drivers/led-backlight/unbind Fix by adding a devlink between the consuming led-backlight device and the supplying LED device, as other drivers and subsystems do as well. Fixes: ae232e45acf9 ("backlight: add led-backlight driver") Signed-off-by: Luca Ceresoli Reviewed-by: Daniel Thompson (RISCstar) Reviewed-by: Herve Codina Tested-by: Alexander Sverdlin Link: https://patch.msgid.link/20250519-led-backlight-add-devlink-to-supplier-class-device-v6-1-845224aeb2ce@bootlin.com Signed-off-by: Lee Jones Signed-off-by: Sasha Levin --- drivers/video/backlight/led_bl.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/video/backlight/led_bl.c b/drivers/video/backlight/led_bl.c index 0e53e427a91dc..9089d17200ec7 100644 --- a/drivers/video/backlight/led_bl.c +++ b/drivers/video/backlight/led_bl.c @@ -209,6 +209,19 @@ static int led_bl_probe(struct platform_device *pdev) return PTR_ERR(priv->bl_dev); } + for (i = 0; i < priv->nb_leds; i++) { + struct device_link *link; + + link = device_link_add(&pdev->dev, priv->leds[i]->dev->parent, + DL_FLAG_AUTOREMOVE_CONSUMER); + if (!link) { + dev_err(&pdev->dev, "Failed to add devlink (consumer %s, supplier %s)\n", + dev_name(&pdev->dev), dev_name(priv->leds[i]->dev->parent)); + backlight_device_unregister(priv->bl_dev); + return -EINVAL; + } + } + for (i = 0; i < priv->nb_leds; i++) { mutex_lock(&priv->leds[i]->led_access); led_sysfs_disable(priv->leds[i]); -- 2.51.0