From patchwork Thu Oct 26 12:49:46 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Lothar_Wa=C3=9Fmann?= X-Patchwork-Id: 10028129 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 8AD316032C for ; Thu, 26 Oct 2017 13:07:25 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7C4CC28DF5 for ; Thu, 26 Oct 2017 13:07:25 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6F8EC28E02; Thu, 26 Oct 2017 13:07:25 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id EC64A28DF5 for ; Thu, 26 Oct 2017 13:07:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932234AbdJZNHY (ORCPT ); Thu, 26 Oct 2017 09:07:24 -0400 Received: from smtprelay04.ispgateway.de ([80.67.31.27]:61687 "EHLO smtprelay04.ispgateway.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932198AbdJZNHX (ORCPT ); Thu, 26 Oct 2017 09:07:23 -0400 Received: from [89.1.81.74] (helo=ipc1.ka-ro) by smtprelay04.ispgateway.de with esmtpsa (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.89) (envelope-from ) id 1e7hbb-0000et-R6; Thu, 26 Oct 2017 14:49:51 +0200 Received: from lothar by ipc1.ka-ro with local (Exim 4.84_2 #2 (Debian)) id 1e7hbZ-00057X-KL; Thu, 26 Oct 2017 14:49:49 +0200 From: =?UTF-8?q?Lothar=20Wa=C3=9Fmann?= To: Bartlomiej Zolnierkiewicz , Daniel Thompson , Jacek Anaszewski , Jingoo Han , Lee Jones , Mark Rutland , Pavel Machek , Richard Purdie , Rob Herring , Thierry Reding , devicetree@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org, linux-pwm@vger.kernel.org Cc: =?UTF-8?q?Lothar=20Wa=C3=9Fmann?= Subject: [PATCH 2/2] backlight: pwm_bl: add configurable delay between re-enabling PWM and switching backlight power on Date: Thu, 26 Oct 2017 14:49:46 +0200 Message-Id: <1509022186-19636-4-git-send-email-LW@KARO-electronics.de> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1509022186-19636-1-git-send-email-LW@KARO-electronics.de> References: <1509022186-19636-1-git-send-email-LW@KARO-electronics.de> MIME-Version: 1.0 X-Df-Sender: bHdAa2Fyby1lbGVjdHJvbmljcy5kZQ== Sender: linux-fbdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP When switching the backlight on, the LCD may need some time to adjust to the configured PWM duty cycle. Add a configurable delay between configuring the PWM and enabling the backlight regulator to account for this. Signed-off-by: Lothar Waßmann --- .../bindings/leds/backlight/pwm-backlight.txt | 4 ++++ drivers/video/backlight/pwm_bl.c | 22 +++++++++++++++++++--- 2 files changed, 23 insertions(+), 3 deletions(-) diff --git a/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt index 764db86..95594c3 100644 --- a/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt +++ b/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt @@ -17,6 +17,10 @@ Optional properties: "pwms" property (see PWM binding[0]) - enable-gpios: contains a single GPIO specifier for the GPIO which enables and disables the backlight (see GPIO binding[1]) + - turn-on-delay-ms: delay in milliseconds between configuring the PWM + and switching PWM on. This may be required to eliminate + flicker when switching the PWM on after it has been + disabled. [0]: Documentation/devicetree/bindings/pwm/pwm.txt [1]: Documentation/devicetree/bindings/gpio/gpio.txt diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c index 921f322..9578f65 100644 --- a/drivers/video/backlight/pwm_bl.c +++ b/drivers/video/backlight/pwm_bl.c @@ -23,6 +23,7 @@ #include #include #include +#include struct pwm_bl_data { struct pwm_device *pwm; @@ -35,6 +36,7 @@ struct pwm_bl_data { struct gpio_desc *enable_gpio; unsigned int scale; bool legacy; + int turn_on_delay_ms; int (*notify)(struct device *, int brightness); void (*notify_after)(struct device *, @@ -52,6 +54,17 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness) pwm_enable(pb->pwm); + if (pb->turn_on_delay_ms > 0) { + dev_dbg(pb->dev, "Sleeping %u..%uµs\n", + pb->turn_on_delay_ms * 1000, + pb->turn_on_delay_ms * 1100); + if (pb->turn_on_delay_ms > 20) + msleep(pb->turn_on_delay_ms); + else + usleep_range(pb->turn_on_delay_ms * 1000, + pb->turn_on_delay_ms * 1100); + } + err = regulator_enable(pb->power_supply); if (err < 0) dev_err(pb->dev, "failed to enable power supply\n"); @@ -108,8 +121,9 @@ static int pwm_backlight_update_status(struct backlight_device *bl) duty_cycle = compute_duty_cycle(pb, brightness); pwm_config(pb->pwm, duty_cycle, pb->period); pwm_backlight_power_on(pb, brightness); - } else + } else { pwm_backlight_power_off(pb); + } if (pb->notify_after) pb->notify_after(pb->dev, brightness); @@ -264,9 +278,9 @@ static int pwm_backlight_probe(struct platform_device *pdev) pb->scale = data->levels[i]; pb->levels = data->levels; - } else + } else { pb->scale = data->max_brightness; - + } pb->notify = data->notify; pb->notify_after = data->notify_after; pb->check_fb = data->check_fb; @@ -329,6 +343,8 @@ static int pwm_backlight_probe(struct platform_device *pdev) goto err_alloc; } + of_property_read_u32(node, "turn-on-delay-ms", &pb->turn_on_delay_ms); + dev_dbg(&pdev->dev, "got pwm for backlight\n"); /*