From patchwork Thu Jul 30 17:22:53 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Philipp Zabel X-Patchwork-Id: 502221 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 4B7DA14090B for ; Fri, 31 Jul 2015 03:23:09 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753421AbbG3RXE (ORCPT ); Thu, 30 Jul 2015 13:23:04 -0400 Received: from metis.ext.pengutronix.de ([92.198.50.35]:58340 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753928AbbG3RXA (ORCPT ); Thu, 30 Jul 2015 13:23:00 -0400 Received: from paszta.hi.4.pengutronix.de ([10.1.0.120] helo=paszta.pengutronix.de.) by metis.ext.pengutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1ZKpgU-00051j-Ua; Thu, 30 Jul 2015 17:23:50 +0200 From: Philipp Zabel To: Thierry Reding Cc: Jingoo Han , Lee Jones , Ajay Kumar , linux-pwm@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@pengutronix.de, Philipp Zabel Subject: [PATCH v2] pwm-backlight: Avoid backlight flicker when probed from DT Date: Thu, 30 Jul 2015 19:22:53 +0200 Message-Id: <1438276973-20920-1-git-send-email-p.zabel@pengutronix.de> X-Mailer: git-send-email 2.1.4 X-SA-Exim-Connect-IP: 10.1.0.120 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-pwm@vger.kernel.org Sender: linux-pwm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org 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 --- Changes since v1: - Also check if the regulator is enabled. If the power supply is disabled, and a phandle points to it, the backlight should stay powered down. --- drivers/video/backlight/pwm_bl.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c index eff379b..31afd6d 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) { @@ -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)) { ret = PTR_ERR(pb->pwm); @@ -321,6 +343,7 @@ 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);