From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752714Ab3JASjp (ORCPT ); Tue, 1 Oct 2013 14:39:45 -0400 Received: from avon.wwwdotorg.org ([70.85.31.133]:35874 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751492Ab3JASjn (ORCPT ); Tue, 1 Oct 2013 14:39:43 -0400 Message-ID: <524B16E8.5080506@wwwdotorg.org> Date: Tue, 01 Oct 2013 12:39:36 -0600 From: Stephen Warren User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130803 Thunderbird/17.0.8 MIME-Version: 1.0 To: Thierry Reding CC: Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Tony Lindgren , Eric Miao , Haojian Zhuang , Ben Dooks , Kukjin Kim , Simon Horman , Magnus Damm , Guan Xuetao , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, openezx-devel@lists.openezx.org, linux-samsung-soc@vger.kernel.org, linux-sh@vger.kernel.org, linux-pwm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 08/10] pwm-backlight: Use new enable_gpio field References: <1379972467-11243-1-git-send-email-treding@nvidia.com> <1379972467-11243-9-git-send-email-treding@nvidia.com> In-Reply-To: <1379972467-11243-9-git-send-email-treding@nvidia.com> X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/23/2013 03:41 PM, Thierry Reding wrote: > Make use of the new enable_gpio field and allow it to be set from DT as > well. Now that all legacy users of platform data have been converted to > initialize this field to an invalid value, it is safe to use the field > from the driver. > diff --git a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt > Optional properties: > + - enable-gpios: a list of GPIOs to enable and disable the backlight That seems to imply that multiple GPIOs are legal. Was that intended? If not, I would suggest: - enable-gpios: contains a single GPIO specifier for the GPIO which enables/disables the backlight. See [1] for the format. > > [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 > @@ -51,12 +55,27 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness, > pb->lth_brightness; > > pwm_config(pb->pwm, duty_cycle, pb->period); > + > + if (gpio_is_valid(pb->enable_gpio)) { > + if (pb->enable_gpio_flags & PWM_BACKLIGHT_GPIO_ACTIVE_LOW) > + gpio_set_value(pb->enable_gpio, 0); > + else > + gpio_set_value(pb->enable_gpio, 1); > + } Feel completely free to ignore this, but when the difference in two code-paths is solely in function parameters, I prefer to calculate the parameter inside the if statement, then call the function outside the conditional code, to highlight the common/different parts: int value; /* or an if statement for the next 1 line, if you don't like ?: */ value = (pb->enable_gpio_flags & PWM_BACKLIGHT_GPIO_ACTIVE_LOW) ? 0 : 1; gpio_set_value((pb->enable_gpio, value); > @@ -148,11 +168,10 @@ static int pwm_backlight_parse_dt(struct device *dev, > + data->enable_gpio = of_get_named_gpio_flags(node, "enable-gpios", 0, > + &flags); > + if (gpio_is_valid(data->enable_gpio) && (flags & OF_GPIO_ACTIVE_LOW)) > + data->enable_gpio_flags |= PWM_BACKLIGHT_GPIO_ACTIVE_LOW; This doesn't seem to handle deferred probe correctly; I would expect something more like: data->enable_gpio = of_get_named_gpio_flags(...); if (data->enable_gpio == -EPROBE_DEFERRED) return data->enable_gpio; if (gpio_is_valid(...)) ... return 0; I suppose it's possible that the value filters down to gpio_request_one() and this actually does work out OK, but that feels very accidental/implicit to me.