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SubjectRe: [PATCH v2 2/3] backlight: tdo24m: add the reset line gpio
On Sat, Dec 16, 2017 at 12:39:50PM +0100, Robert Jarzmik wrote:
> Daniel Thompson <daniel.thompson@linaro.org> writes:
> > On Fri, Oct 13, 2017 at 09:42:48PM +0200, Robert Jarzmik wrote:
> >> The Toppoly panels have a global reset line. Add an optional gpio
> >> control for this line, for platforms which have the ability to drive it.
> >>
> >> Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
> >> ---
> >> drivers/video/backlight/tdo24m.c | 3 +++
> >> 1 file changed, 3 insertions(+)
> >>
> >> diff --git a/drivers/video/backlight/tdo24m.c b/drivers/video/backlight/tdo24m.c
> >> index e4bd63e9db6b..e4b2dfabf192 100644
> >> --- a/drivers/video/backlight/tdo24m.c
> >> +++ b/drivers/video/backlight/tdo24m.c
> >> @@ -10,6 +10,7 @@
> >> */
> >>
> >> #include <linux/module.h>
> >> +#include <linux/gpio/consumer.h>
> >> #include <linux/kernel.h>
> >> #include <linux/init.h>
> >> #include <linux/device.h>
> >> @@ -32,6 +33,7 @@ struct tdo24m {
> >> struct spi_message msg;
> >> struct spi_transfer xfer;
> >> uint8_t *buf;
> >> + struct gpio_desc *xres;
> >
> > Why do we need a write-only variable?
> It's written to by devm_gpiod_get() below.

Yes, but it not *read* anywhere because we rely on devm to release the GPIO.
Why do we need a write-only variable?


> >> + lcd->xres = devm_gpiod_get(&spi->dev, "reset", GPIOD_OUT_LOW);
> >
> > devm_gpiod_get_optional() would be better, if only for its commenting
> > value.
> Yes, you're perfectly right.
>
> > Also, this adds a new optional property, doesn't the devicetree binding
> > docs need to be update to match this?
> Ah yes, that too. I'll add it for v3.

Thanks!


Daniel.

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