From patchwork Mon Sep 20 16:41:56 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 514342 Delivered-To: patch@linaro.org Received: by 2002:a02:c816:0:0:0:0:0 with SMTP id p22csp2264904jao; Mon, 20 Sep 2021 10:19:18 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyMBhNpK8qCIAIvVKoFq/kLpuXM6JqMuGKxLo5oEXdIWbHEreCBeKdh760Fy2LhZU7ySxMo X-Received: by 2002:a05:6638:3890:: with SMTP id b16mr20824317jav.65.1632158349939; Mon, 20 Sep 2021 10:19:09 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1632158349; cv=none; d=google.com; s=arc-20160816; b=oouSrEgK7/KSvhp3AR1n1dbkr/ROYxLMs1MZXUsxoUBqFM0HoTRoS+r026YDgP0+Hl X5e8aOsZp5U9swhf+ZMj5lI+ihCzZcNcYpOXqv13VbZIafvApmxqJFs3sSfV7ewo4Oqc nEVBrgACryT//RgIGJiZus7uaAyy28Inwm80tWDU3otpU3LdJbdrWraiu8waWOrWedmi e1pMhQr7X4EKGeE99WrG2DV5t+q1LARjttGhu1BKufi11VN3ixMt+APCSms24TX0TP5N ne8ou/UVFEY7uJVc+DPgEKzdudyYeRI6tCddgxm94uK6n8u0mmm4aM8vjYq0i2Bf9VE6 EsWg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :user-agent:references:in-reply-to:message-id:date:subject:cc:to :from:dkim-signature; bh=CiL9Uu5ukrq679jxxyvJEYqR4BtEvB31JRawFUvvCgI=; b=NtTR+F6pb+Vifk7RFciavo9ZuboMwKm29LJwZxED0dBAMMzFnoZOG6ceuIHgm8ckq2 /jjAtGzNect9jKIF1EjnI2P7e8KHaEqw3WIbb1qODpAm2ncWFBYWi7lRk2eJOmMkdirf jNMUFX8bFEokA1+y514t0aeq/6SXJ7zrvOP6BUBnDKVlcvoWXjy6Ffd0wX3wmULbvBz2 wnpGOlfQAuxqvajWsBhkQX0FdTKWMWQ2K/30Y6Fa1ts5cyHeOMoVTU2fdgDVCQbz9Qdp hvYTofp73+7pHsHyvr1ZP7qP1WGv5MnlncDhRjiYe3S1iHkLsGiVKY8ATT57K4uC0g2J PsNw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b=djneZY6G; spf=pass (google.com: domain of stable-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=stable-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id h22si13620601jal.57.2021.09.20.10.19.09; Mon, 20 Sep 2021 10:19:09 -0700 (PDT) Received-SPF: pass (google.com: domain of stable-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b=djneZY6G; spf=pass (google.com: domain of stable-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=stable-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348892AbhITRUf (ORCPT + 11 others); Mon, 20 Sep 2021 13:20:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:46190 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346711AbhITRSn (ORCPT ); Mon, 20 Sep 2021 13:18:43 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6053761A2F; Mon, 20 Sep 2021 16:59:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1632157191; bh=HPXnj/Qb0YFHLsTSz6Kt0aSpTtygeDnH2kVS/uy0QYE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=djneZY6GIbJrdwKfonZLsUL5lUpDdX/fCaewfMehtTA0DNsXDEjtOOkyGyefvcS6V 1hXZM4JcwpDsvafesHNHGT3mEd1iujl9d1gFp+icYA63p5nk0BB3nsyGc8mKEz59W5 YZb7NCEFu+7njwiTSxbeta+6TVHabSmiO4efe9r0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Marek Vasut , Daniel Thompson , Lee Jones Subject: [PATCH 4.14 095/217] backlight: pwm_bl: Improve bootloader/kernel device handover Date: Mon, 20 Sep 2021 18:41:56 +0200 Message-Id: <20210920163927.857122329@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210920163924.591371269@linuxfoundation.org> References: <20210920163924.591371269@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Daniel Thompson commit 79fad92f2e596f5a8dd085788a24f540263ef887 upstream. Currently there are (at least) two problems in the way pwm_bl starts managing the enable_gpio pin. Both occur when the backlight is initially off and the driver finds the pin not already in output mode and, as a result, unconditionally switches it to output-mode and asserts the signal. Problem 1: This could cause the backlight to flicker since, at this stage in driver initialisation, we have no idea what the PWM and regulator are doing (an unconfigured PWM could easily "rest" at 100% duty cycle). Problem 2: This will cause us not to correctly honour the post_pwm_on_delay (which also risks flickers). Fix this by moving the code to configure the GPIO output mode until after we have examines the handover state. That allows us to initialize enable_gpio to off if the backlight is currently off and on if the backlight is on. Cc: stable@vger.kernel.org Reported-by: Marek Vasut Signed-off-by: Daniel Thompson Acked-by: Marek Vasut Tested-by: Marek Vasut Signed-off-by: Lee Jones Signed-off-by: Greg Kroah-Hartman --- drivers/video/backlight/pwm_bl.c | 54 ++++++++++++++++++++------------------- 1 file changed, 28 insertions(+), 26 deletions(-) --- a/drivers/video/backlight/pwm_bl.c +++ b/drivers/video/backlight/pwm_bl.c @@ -199,6 +199,33 @@ static int pwm_backlight_parse_dt(struct static int pwm_backlight_initial_power_state(const struct pwm_bl_data *pb) { struct device_node *node = pb->dev->of_node; + bool active = true; + + /* + * If the enable GPIO is present, observable (either as input + * or output) and off then the backlight is not currently active. + * */ + if (pb->enable_gpio && gpiod_get_value_cansleep(pb->enable_gpio) == 0) + active = false; + + if (!regulator_is_enabled(pb->power_supply)) + active = false; + + if (!pwm_is_enabled(pb->pwm)) + active = false; + + /* + * Synchronize the enable_gpio with the observed state of the + * hardware. + */ + if (pb->enable_gpio) + gpiod_direction_output(pb->enable_gpio, active); + + /* + * Do not change pb->enabled here! pb->enabled essentially + * tells us if we own one of the regulator's use counts and + * right now we do not. + */ /* Not booted with device tree or no phandle link to the node */ if (!node || !node->phandle) @@ -210,20 +237,7 @@ static int pwm_backlight_initial_power_s * assume that another driver will enable the backlight at the * appropriate time. Therefore, if it is disabled, keep it so. */ - - /* if the enable GPIO is disabled, do not enable the backlight */ - if (pb->enable_gpio && gpiod_get_value_cansleep(pb->enable_gpio) == 0) - return FB_BLANK_POWERDOWN; - - /* The regulator is disabled, do not enable the backlight */ - if (!regulator_is_enabled(pb->power_supply)) - return FB_BLANK_POWERDOWN; - - /* The PWM is disabled, keep it like this */ - if (!pwm_is_enabled(pb->pwm)) - return FB_BLANK_POWERDOWN; - - return FB_BLANK_UNBLANK; + return active ? FB_BLANK_UNBLANK: FB_BLANK_POWERDOWN; } static int pwm_backlight_probe(struct platform_device *pdev) @@ -300,18 +314,6 @@ static int pwm_backlight_probe(struct pl pb->enable_gpio = gpio_to_desc(data->enable_gpio); } - /* - * If the GPIO is not known to be already configured as output, that - * is, if gpiod_get_direction returns either 1 or -EINVAL, change the - * direction to output and set the GPIO as active. - * Do not force the GPIO to active when it was already output as it - * could cause backlight flickering or we would enable the backlight too - * early. Leave the decision of the initial backlight state for later. - */ - if (pb->enable_gpio && - gpiod_get_direction(pb->enable_gpio) != 0) - gpiod_direction_output(pb->enable_gpio, 1); - pb->power_supply = devm_regulator_get(&pdev->dev, "power"); if (IS_ERR(pb->power_supply)) { ret = PTR_ERR(pb->power_supply);