On Fri, 24 Mar 2017, Daniel Thompson wrote:
> 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 <geert+renesas@xxxxxxxxx>
> >
> > Acked-by: Daniel Thommpson <daniel.thompson@xxxxxxxxxx>
>
> Actually, it would be better if there only one m...
>
> Acked-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
You probably don't want to be typing out your Acks manually every
time. Can you set a key combination in your editor?
> > > ---
> > > 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");
> > >
> >
>
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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