From patchwork Thu Oct 29 15:51:46 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Philipp Zabel X-Patchwork-Id: 7519661 Return-Path: X-Original-To: patchwork-linux-fbdev@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 89E979F36A for ; Thu, 29 Oct 2015 15:51:57 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id A5E472080C for ; Thu, 29 Oct 2015 15:51:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A7D3B20667 for ; Thu, 29 Oct 2015 15:51:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752268AbbJ2Pvz (ORCPT ); Thu, 29 Oct 2015 11:51:55 -0400 Received: from metis.ext.4.pengutronix.de ([92.198.50.35]:40063 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751801AbbJ2Pvy (ORCPT ); Thu, 29 Oct 2015 11:51:54 -0400 Received: from dude.hi.4.pengutronix.de ([10.1.0.7] helo=dude.pengutronix.de.) by metis.ext.pengutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1ZrpUT-0000G3-50; Thu, 29 Oct 2015 16:51:49 +0100 From: Philipp Zabel To: Thierry Reding Cc: Jingoo Han , Lee Jones , Ajay Kumar , YH Huang , Christian Gmeiner , linux-pwm@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kernel@pengutronix.de, Philipp Zabel Subject: [PATCH] pwm-backlight: Avoid backlight flicker when probed from DT Date: Thu, 29 Oct 2015 16:51:46 +0100 Message-Id: <1446133906-3076-1-git-send-email-p.zabel@pengutronix.de> X-Mailer: git-send-email 2.6.1 X-SA-Exim-Connect-IP: 10.1.0.7 X-SA-Exim-Mail-From: p.zabel@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-fbdev@vger.kernel.org Sender: linux-fbdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP If the driver is probed from the device tree, and there is a phandle property set on it, and the enable GPIO is already configured as output, and the backlight is currently disabled, keep it disabled. If all these conditions are met, assume there will be some other driver that can enable the backlight at the appropriate time. Signed-off-by: Philipp Zabel Reviewed-by: Christian Gmeiner --- Changes since v2: - Leave GPIO configuration as is (GPIOD_ASIS) when requesting, so we can actually check the initial state. --- drivers/video/backlight/pwm_bl.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c index ae3c6b6..8e9c261 100644 --- a/drivers/video/backlight/pwm_bl.c +++ b/drivers/video/backlight/pwm_bl.c @@ -199,6 +199,8 @@ static int pwm_backlight_probe(struct platform_device *pdev) struct backlight_properties props; struct backlight_device *bl; struct pwm_bl_data *pb; + int initial_blank = FB_BLANK_UNBLANK; + bool phandle; int ret; if (!data) { @@ -242,7 +244,7 @@ static int pwm_backlight_probe(struct platform_device *pdev) pb->enabled = false; pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable", - GPIOD_OUT_HIGH); + GPIOD_ASIS); if (IS_ERR(pb->enable_gpio)) { ret = PTR_ERR(pb->enable_gpio); goto err_alloc; @@ -264,12 +266,32 @@ static int pwm_backlight_probe(struct platform_device *pdev) pb->enable_gpio = gpio_to_desc(data->enable_gpio); } + phandle = of_find_property(pdev->dev.of_node, "phandle", NULL) != NULL; + + if (pb->enable_gpio) { + /* + * If the driver is probed from the device tree and there is a + * phandle link pointing to the backlight node, it is safe to + * assume that another driver will enable the backlight at the + * appropriate time. Therefore, if it is disabled, keep it so. + */ + if (phandle && + gpiod_get_direction(pb->enable_gpio) == GPIOF_DIR_OUT && + gpiod_get_value(pb->enable_gpio) == 0) + initial_blank = FB_BLANK_POWERDOWN; + else + 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); goto err_alloc; } + if (phandle && !regulator_is_enabled(pb->power_supply)) + initial_blank = FB_BLANK_POWERDOWN; + pb->pwm = devm_pwm_get(&pdev->dev, NULL); if (IS_ERR(pb->pwm) && PTR_ERR(pb->pwm) != -EPROBE_DEFER && !pdev->dev.of_node) { @@ -320,6 +342,7 @@ static int pwm_backlight_probe(struct platform_device *pdev) } bl->props.brightness = data->dft_brightness; + bl->props.power = initial_blank; backlight_update_status(bl); platform_set_drvdata(pdev, bl);