From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Ujfalusi Date: Thu, 23 Mar 2017 21:11:13 +0000 Subject: Re: [PATCH] backlight: pwm_bl: Fix GPIO out for unimplemented .get_direction() Message-Id: List-Id: References: <1490203285-28324-1-git-send-email-geert+renesas@glider.be> In-Reply-To: <1490203285-28324-1-git-send-email-geert+renesas@glider.be> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: Geert Uytterhoeven , Thierry Reding , Lee Jones , Daniel Thompson , Jingoo Han , Bartlomiej Zolnierkiewicz Cc: Philipp Zabel , linux-pwm@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org On 03/22/2017 07:21 PM, 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. The platforms I have tested the gpio drivers do implement the get_direction= ()=20 callback and I was not aware of this behaviour. > 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 Reviewed-by: Peter Ujfalusi > --- > 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/p= wm_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_devi= ce *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) =3D GPIOF_DIR_IN) > + gpiod_get_direction(pb->enable_gpio) !=3D GPIOF_DIR_OUT) > gpiod_direction_output(pb->enable_gpio, 1); > > pb->power_supply =3D devm_regulator_get(&pdev->dev, "power"); > --=20 P=E9ter