Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966620AbdCXQn6 (ORCPT ); Fri, 24 Mar 2017 12:43:58 -0400 Received: from mail-wr0-f182.google.com ([209.85.128.182]:32768 "EHLO mail-wr0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965571AbdCXQnr (ORCPT ); Fri, 24 Mar 2017 12:43:47 -0400 Subject: Re: [PATCH] backlight: pwm_bl: Fix GPIO out for unimplemented .get_direction() To: Geert Uytterhoeven , Thierry Reding , Lee Jones , Jingoo Han , Bartlomiej Zolnierkiewicz References: <1490203285-28324-1-git-send-email-geert+renesas@glider.be> Cc: Peter Ujfalusi , Philipp Zabel , linux-pwm@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org From: Daniel Thompson Message-ID: <6960ceea-5e34-3435-eecb-10e18322b15c@linaro.org> Date: Fri, 24 Mar 2017 16:43:44 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2364 Lines: 65 On 24/03/17 16:42, Daniel Thompson wrote: > On 22/03/17 17:21, Geert Uytterhoeven wrote: >> Commit 7613c922315e308a ("backlight: pwm_bl: Move the checks for initial >> power state to a separate function") not just moved some code, but made >> slight changes in semantics. >> >> If a gpiochip doesn't implement the optional .get_direction() callback, >> gpiod_get_direction always returns -EINVAL, which is never equal to >> GPIOF_DIR_IN, leading to the GPIO not being configured for output. >> >> To avoid this, invert the test and check for not GPIOF_DIR_OUT instead, >> like the original code did. >> >> This restores the display on r8a7740/armadillo. >> >> Fixes: 7613c922315e308a ("backlight: pwm_bl: Move the checks for >> initial power state to a separate function") >> Signed-off-by: Geert Uytterhoeven > > Acked-by: Daniel Thommpson Actually, it would be better if there only one m... Acked-by: Daniel Thompson Daniel. > > >> --- >> drivers/video/backlight/pwm_bl.c | 7 ++++--- >> 1 file changed, 4 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/video/backlight/pwm_bl.c >> b/drivers/video/backlight/pwm_bl.c >> index d7efcb632f7d9dde..002f1ce22bd02032 100644 >> --- a/drivers/video/backlight/pwm_bl.c >> +++ b/drivers/video/backlight/pwm_bl.c >> @@ -297,14 +297,15 @@ static int pwm_backlight_probe(struct >> platform_device *pdev) >> } >> >> /* >> - * If the GPIO is configured as input, change the direction to >> output >> - * and set the GPIO as active. >> + * If the GPIO is not known to be already configured as output, that >> + * is, if gpiod_get_direction returns either GPIOF_DIR_IN or >> -EINVAL, >> + * change the direction to output and set the GPIO as active. >> * Do not force the GPIO to active when it was already output as it >> * could cause backlight flickering or we would enable the >> backlight too >> * early. Leave the decision of the initial backlight state for >> later. >> */ >> if (pb->enable_gpio && >> - gpiod_get_direction(pb->enable_gpio) == GPIOF_DIR_IN) >> + gpiod_get_direction(pb->enable_gpio) != GPIOF_DIR_OUT) >> gpiod_direction_output(pb->enable_gpio, 1); >> >> pb->power_supply = devm_regulator_get(&pdev->dev, "power"); >> >