From patchwork Fri Oct 19 09:06:28 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexandre Courbot X-Patchwork-Id: 1617271 Return-Path: X-Original-To: patchwork-linux-fbdev@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork2.kernel.org (Postfix) with ESMTP id B0791DF26F for ; Fri, 19 Oct 2012 09:06:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757360Ab2JSJFs (ORCPT ); Fri, 19 Oct 2012 05:05:48 -0400 Received: from hqemgate04.nvidia.com ([216.228.121.35]:18092 "EHLO hqemgate04.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753531Ab2JSJFp (ORCPT ); Fri, 19 Oct 2012 05:05:45 -0400 Received: from hqnvupgp08.nvidia.com (Not Verified[216.228.121.13]) by hqemgate04.nvidia.com id ; Fri, 19 Oct 2012 02:04:34 -0700 Received: from hqemhub03.nvidia.com ([172.17.108.22]) by hqnvupgp08.nvidia.com (PGP Universal service); Fri, 19 Oct 2012 02:05:06 -0700 X-PGP-Universal: processed; by hqnvupgp08.nvidia.com on Fri, 19 Oct 2012 02:05:06 -0700 Received: from percival.nvidia.com (172.20.144.16) by hqemhub03.nvidia.com (172.20.150.15) with Microsoft SMTP Server (TLS) id 8.3.279.1; Fri, 19 Oct 2012 02:05:04 -0700 From: Alexandre Courbot To: Stephen Warren , Thierry Reding , Simon Glass , Grant Likely , Rob Herring , Mark Brown , Anton Vorontsov , David Woodhouse , Arnd Bergmann CC: Leela Krishna Amudala , , , , , , , Alexandre Courbot Subject: [PATCH v7 2/3] pwm_backlight: use power sequences Date: Fri, 19 Oct 2012 18:06:28 +0900 Message-ID: <1350637589-7405-3-git-send-email-acourbot@nvidia.com> X-Mailer: git-send-email 1.7.12.3 In-Reply-To: <1350637589-7405-1-git-send-email-acourbot@nvidia.com> References: <1350637589-7405-1-git-send-email-acourbot@nvidia.com> X-NVConfidentiality: public MIME-Version: 1.0 Sender: linux-fbdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org Make use of the power sequences specified in the device tree or platform data to control how the backlight is powered on and off. Signed-off-by: Alexandre Courbot --- .../bindings/video/backlight/pwm-backlight.txt | 72 ++++++++- drivers/video/backlight/Kconfig | 1 + drivers/video/backlight/pwm_bl.c | 161 ++++++++++++++++----- include/linux/pwm_backlight.h | 18 ++- 4 files changed, 213 insertions(+), 39 deletions(-) diff --git a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt index 1e4fc72..3ba25ea 100644 --- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt +++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt @@ -14,15 +14,83 @@ Required properties: Optional properties: - pwm-names: a list of names for the PWM devices specified in the "pwms" property (see PWM binding[0]) + - low-threshold-brightness: brightness threshold low level. Sets the lowest + brightness value. + On some panels the backlight misbehaves if the duty cycle percentage of the + PWM wave is less than a certain level (say 20%). In this example the user + can set low-threshold-brightness to a value above 50 (ie, 20% of 255), thus + preventing the PWM duty cycle from going too low. + On setting low-threshold-brightness the range of brightness levels is + calculated in the range low-threshold-brightness to the maximum value in + brightness-levels, described above. + - pwm-names: name for the PWM device specified in the "pwms" property (see PWM + binding[0]). Necessary if power sequences are used + - power-sequences: Power sequences (see Power sequences[1]) used to bring the + backlight on and off. If this property is present, then two power + sequences named "power-on" and "power-off" must be defined to control how + the backlight is to be powered on and off. These sequences must reference + the PWM specified in the pwms property by its name, and can also reference + other resources supported by the power sequences mechanism [0]: Documentation/devicetree/bindings/pwm/pwm.txt +[1]: Documentation/devicetree/bindings/power/power_seq.txt Example: backlight { compatible = "pwm-backlight"; - pwms = <&pwm 0 5000000>; - brightness-levels = <0 4 8 16 32 64 128 255>; default-brightness-level = <6>; + low-threshold-brightness = <50>; + + /* resources used by the power sequences */ + pwms = <&pwm 0 5000000>; + pwm-names = "backlight"; + power-supply = <&backlight_reg>; + + power-sequences { + power-on { + step0 { + type = "regulator"; + id = "power"; + enable; + }; + step1 { + type = "delay"; + delay = <10000>; + }; + step2 { + type = "pwm"; + id = "backlight"; + enable; + }; + step3 { + type = "gpio"; + gpio = <&gpio 28 0>; + value = <1>; + }; + }; + + power-off { + step0 { + type = "gpio"; + gpio = <&gpio 28 0>; + value = <0>; + }; + step1 { + type = "pwm"; + id = "backlight"; + disable; + }; + step2 { + type = "delay"; + delay = <10000>; + }; + step3 { + type = "regulator"; + id = "power"; + disable; + }; + }; + }; }; diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig index c101697..c2e5f79 100644 --- a/drivers/video/backlight/Kconfig +++ b/drivers/video/backlight/Kconfig @@ -239,6 +239,7 @@ config BACKLIGHT_CARILLO_RANCH config BACKLIGHT_PWM tristate "Generic PWM based Backlight Driver" depends on PWM + select POWER_SEQ help If you have a LCD backlight adjustable by PWM, say Y to enable this driver. diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c index 069983c..e607c6e 100644 --- a/drivers/video/backlight/pwm_bl.c +++ b/drivers/video/backlight/pwm_bl.c @@ -27,6 +27,12 @@ struct pwm_bl_data { unsigned int period; unsigned int lth_brightness; unsigned int *levels; + bool enabled; + struct power_seq_set power_seqs; + struct power_seq *power_on_seq; + struct power_seq *power_off_seq; + + /* Legacy callbacks */ int (*notify)(struct device *, int brightness); void (*notify_after)(struct device *, @@ -35,6 +41,52 @@ struct pwm_bl_data { void (*exit)(struct device *); }; +static void pwm_backlight_on(struct backlight_device *bl) +{ + struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev); + int ret; + + if (pb->enabled) + return; + + if (pb->power_on_seq) { + ret = power_seq_run(pb->power_on_seq); + if (ret < 0) { + dev_err(&bl->dev, "cannot run power on sequence\n"); + return; + } + } else { + /* legacy framework */ + pwm_config(pb->pwm, 0, pb->period); + pwm_disable(pb->pwm); + } + + pb->enabled = true; +} + +static void pwm_backlight_off(struct backlight_device *bl) +{ + struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev); + int ret; + + if (!pb->enabled) + return; + + if (pb->power_off_seq) { + ret = power_seq_run(pb->power_off_seq); + if (ret < 0) { + dev_err(&bl->dev, "cannot run power off sequence\n"); + return; + } + } else { + /* legacy framework */ + pwm_enable(pb->pwm); + return; + } + + pb->enabled = false; +} + static int pwm_backlight_update_status(struct backlight_device *bl) { struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev); @@ -51,8 +103,7 @@ static int pwm_backlight_update_status(struct backlight_device *bl) brightness = pb->notify(pb->dev, brightness); if (brightness == 0) { - pwm_config(pb->pwm, 0, pb->period); - pwm_disable(pb->pwm); + pwm_backlight_off(bl); } else { int duty_cycle; @@ -66,7 +117,7 @@ static int pwm_backlight_update_status(struct backlight_device *bl) duty_cycle = pb->lth_brightness + (duty_cycle * (pb->period - pb->lth_brightness) / max); pwm_config(pb->pwm, duty_cycle, pb->period); - pwm_enable(pb->pwm); + pwm_backlight_on(bl); } if (pb->notify_after) @@ -145,11 +196,10 @@ static int pwm_backlight_parse_dt(struct device *dev, data->max_brightness--; } - /* - * TODO: Most users of this driver use a number of GPIOs to control - * backlight power. Support for specifying these needs to be - * added. - */ + /* read power sequences */ + data->power_seqs = devm_of_parse_power_seq_set(dev); + if (IS_ERR(data->power_seqs)) + return PTR_ERR(data->power_seqs); return 0; } @@ -172,6 +222,7 @@ static int pwm_backlight_probe(struct platform_device *pdev) { struct platform_pwm_backlight_data *data = pdev->dev.platform_data; struct platform_pwm_backlight_data defdata; + struct power_seq_resource *res; struct backlight_properties props; struct backlight_device *bl; struct pwm_bl_data *pb; @@ -180,7 +231,9 @@ static int pwm_backlight_probe(struct platform_device *pdev) if (!data) { ret = pwm_backlight_parse_dt(&pdev->dev, &defdata); - if (ret < 0) { + if (ret == -EPROBE_DEFER) { + return ret; + } else if (ret < 0) { dev_err(&pdev->dev, "failed to find platform data\n"); return ret; } @@ -201,6 +254,68 @@ static int pwm_backlight_probe(struct platform_device *pdev) goto err_alloc; } + if (data->power_seqs) { + /* use power sequences */ + struct power_seq_set *seqs = &pb->power_seqs; + + power_seq_set_init(seqs, &pdev->dev); + power_seq_set_add_sequences(seqs, data->power_seqs); + + /* Check that the required sequences are here */ + pb->power_on_seq = power_seq_lookup(seqs, "power-on"); + if (!pb->power_on_seq) { + dev_err(&pdev->dev, "missing power-on sequence\n"); + return -EINVAL; + } + pb->power_off_seq = power_seq_lookup(seqs, "power-off"); + if (!pb->power_off_seq) { + dev_err(&pdev->dev, "missing power-off sequence\n"); + return -EINVAL; + } + + /* we must have exactly one PWM resource for this driver */ + power_seq_for_each_resource(res, seqs) { + if (res->type != POWER_SEQ_PWM) + continue; + if (pb->pwm) { + dev_err(&pdev->dev, "more than one PWM used\n"); + return -EINVAL; + } + /* keep the pwm at hand */ + pb->pwm = res->pwm.pwm; + } + /* from here we should have a PWM */ + if (!pb->pwm) { + dev_err(&pdev->dev, "no PWM defined!\n"); + return -EINVAL; + } + } else { + /* use legacy interface */ + pb->pwm = devm_pwm_get(&pdev->dev, NULL); + if (IS_ERR(pb->pwm)) { + dev_err(&pdev->dev, + "unable to request PWM, trying legacy API\n"); + + pb->pwm = pwm_request(data->pwm_id, "pwm-backlight"); + if (IS_ERR(pb->pwm)) { + dev_err(&pdev->dev, + "unable to request legacy PWM\n"); + ret = PTR_ERR(pb->pwm); + goto err_alloc; + } + } + + dev_dbg(&pdev->dev, "got pwm for backlight\n"); + + /* + * The DT case will set the pwm_period_ns field to 0 and store + * the period, parsed from the DT, in the PWM device. For the + * non-DT case, set the period from platform data. + */ + if (data->pwm_period_ns > 0) + pwm_set_period(pb->pwm, data->pwm_period_ns); + } + if (data->levels) { max = data->levels[data->max_brightness]; pb->levels = data->levels; @@ -213,28 +328,6 @@ static int pwm_backlight_probe(struct platform_device *pdev) pb->exit = data->exit; pb->dev = &pdev->dev; - pb->pwm = devm_pwm_get(&pdev->dev, NULL); - if (IS_ERR(pb->pwm)) { - dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n"); - - pb->pwm = pwm_request(data->pwm_id, "pwm-backlight"); - if (IS_ERR(pb->pwm)) { - dev_err(&pdev->dev, "unable to request legacy PWM\n"); - ret = PTR_ERR(pb->pwm); - goto err_alloc; - } - } - - dev_dbg(&pdev->dev, "got pwm for backlight\n"); - - /* - * The DT case will set the pwm_period_ns field to 0 and store the - * period, parsed from the DT, in the PWM device. For the non-DT case, - * set the period from platform data. - */ - if (data->pwm_period_ns > 0) - pwm_set_period(pb->pwm, data->pwm_period_ns); - pb->period = pwm_get_period(pb->pwm); pb->lth_brightness = data->lth_brightness * (pb->period / max); @@ -267,8 +360,7 @@ static int pwm_backlight_remove(struct platform_device *pdev) struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev); backlight_device_unregister(bl); - pwm_config(pb->pwm, 0, pb->period); - pwm_disable(pb->pwm); + pwm_backlight_off(bl); if (pb->exit) pb->exit(&pdev->dev); return 0; @@ -282,8 +374,7 @@ static int pwm_backlight_suspend(struct device *dev) if (pb->notify) pb->notify(pb->dev, 0); - pwm_config(pb->pwm, 0, pb->period); - pwm_disable(pb->pwm); + pwm_backlight_off(bl); if (pb->notify_after) pb->notify_after(pb->dev, 0); return 0; diff --git a/include/linux/pwm_backlight.h b/include/linux/pwm_backlight.h index 56f4a86..0dcec1d 100644 --- a/include/linux/pwm_backlight.h +++ b/include/linux/pwm_backlight.h @@ -5,14 +5,28 @@ #define __LINUX_PWM_BACKLIGHT_H #include +#include struct platform_pwm_backlight_data { - int pwm_id; unsigned int max_brightness; unsigned int dft_brightness; unsigned int lth_brightness; - unsigned int pwm_period_ns; unsigned int *levels; + /* + * New interface using power sequences. Must include exactly + * two power sequences named 'power-on' and 'power-off'. If NULL, + * the legacy interface is used. + */ + struct platform_power_seq_set *power_seqs; + + /* + * Legacy interface - use power sequences instead! + * + * pwm_id and pwm_period_ns need only be specified + * if get_pwm(dev, NULL) would return NULL. + */ + int pwm_id; + unsigned int pwm_period_ns; int (*init)(struct device *dev); int (*notify)(struct device *dev, int brightness); void (*notify_after)(struct device *dev, int brightness);