From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753136AbbJWXoN (ORCPT ); Fri, 23 Oct 2015 19:44:13 -0400 Received: from mail.kmu-office.ch ([178.209.48.109]:56696 "EHLO mail.kmu-office.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752085AbbJWXoL (ORCPT ); Fri, 23 Oct 2015 19:44:11 -0400 From: Stefan Agner To: jingoohan1@gmail.com, lee.jones@linaro.org Cc: linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, Stefan Agner Subject: [PATCH] backlight: gpio-backlight: use default-on on GPIO request Date: Fri, 23 Oct 2015 16:44:43 -0700 Message-Id: <1445643883-30726-1-git-send-email-stefan@agner.ch> X-Mailer: git-send-email 2.6.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There are situations where the backlight should be on at boot time (e.g. if the boot loader already turned the display on). The DT bindings specify the "default-on" property for that purpose. Currently, the initial state of the GPIO at request time is always set to logical off (high or low depending on whether it is an active high or low GPIO). Since the GPIO is requested as an output, the GPIO will be driven low for a short period of time, which leads to a flickering display in the above use-case. Initialize the GPIO depending on the default-on property to be logical on or off. Signed-off-by: Stefan Agner --- drivers/video/backlight/gpio_backlight.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c index 5fbbc2e..1813441 100644 --- a/drivers/video/backlight/gpio_backlight.c +++ b/drivers/video/backlight/gpio_backlight.c @@ -89,6 +89,7 @@ static int gpio_backlight_probe(struct platform_device *pdev) struct backlight_device *bl; struct gpio_backlight *gbl; struct device_node *np = pdev->dev.of_node; + unsigned long flags = GPIOF_DIR_OUT; int ret; if (!pdata && !np) { @@ -114,9 +115,12 @@ static int gpio_backlight_probe(struct platform_device *pdev) gbl->def_value = pdata->def_value; } - ret = devm_gpio_request_one(gbl->dev, gbl->gpio, GPIOF_DIR_OUT | - (gbl->active ? GPIOF_INIT_LOW - : GPIOF_INIT_HIGH), + if (gbl->active) + flags |= gbl->def_value ? GPIOF_INIT_HIGH : GPIOF_INIT_LOW; + else + flags |= gbl->def_value ? GPIOF_INIT_LOW : GPIOF_INIT_HIGH; + + ret = devm_gpio_request_one(gbl->dev, gbl->gpio, flags, pdata ? pdata->name : "backlight"); if (ret < 0) { dev_err(&pdev->dev, "unable to request GPIO\n"); -- 2.6.2