Hi,
Am Freitag, den 12.06.2015, 18:26 +0200 schrieb Philipp Zabel:
> If the driver is probed from the device tree, and there is a phandle
> property set on it, and the enable GPIO is already configured as output,
> and the backlight is currently disabled, keep it disabled.
> If all these conditions are met, assume there will be some other driver
> that can enable the backlight at the appropriate time.
>
> Signed-off-by: Philipp Zabel <[email protected]>
> ---
> I have seen the thread at https://lkml.org/lkml/2014/7/31/259, but I'm not
> sure if it has come to a resolution. This is what I think could be useful
> to keep the current default behaviour of enabling the backlight while at the
> same time allowing to keep it disabled if we are absolutely certain that the
> backlight is currently off, and we think there is some other driver that will
> control it:
do you have any comments on this? Would the conditions mentioned above
be sufficient for your use cases?
best regards
Philipp
> ---
> drivers/video/backlight/pwm_bl.c | 19 +++++++++++++++++--
> 1 file changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/video/backlight/pwm_bl.c
> b/drivers/video/backlight/pwm_bl.c
> index 6897f1c..dcb6bfb 100644
> --- a/drivers/video/backlight/pwm_bl.c
> +++ b/drivers/video/backlight/pwm_bl.c
> @@ -199,6 +199,7 @@ static int pwm_backlight_probe(struct platform_device
> *pdev)
> struct backlight_properties props;
> struct backlight_device *bl;
> struct pwm_bl_data *pb;
> + int initial_blank = FB_BLANK_UNBLANK;
> int ret;
>
> if (!data) {
> @@ -263,8 +264,21 @@ static int pwm_backlight_probe(struct platform_device
> *pdev)
> pb->enable_gpio = gpio_to_desc(data->enable_gpio);
> }
>
> - if (pb->enable_gpio)
> - gpiod_direction_output(pb->enable_gpio, 1);
> + if (pb->enable_gpio) {
> + /*
> + * If the driver is probed from the device tree and there is a
> + * phandle link pointing to the backlight node, it is safe to
> + * assume that another driver will enable the backlight at the
> + * appropriate time. Therefore, if it is disabled, keep it so.
> + */
> + if (of_find_property(pdev->dev.of_node, "phandle", NULL) &&
> + gpiod_get_direction(pb->enable_gpio) == GPIOF_DIR_OUT &&
> + gpiod_get_value(pb->enable_gpio) == 0) {
> + initial_blank = FB_BLANK_POWERDOWN;
> + } else {
> + gpiod_direction_output(pb->enable_gpio, 1);
> + }
> + }
>
> pb->power_supply = devm_regulator_get(&pdev->dev, "power");
> if (IS_ERR(pb->power_supply)) {
> @@ -323,6 +337,7 @@ static int pwm_backlight_probe(struct platform_device
> *pdev)
> }
>
> bl->props.brightness = data->dft_brightness;
> + bl->props.power = initial_blank;
> backlight_update_status(bl);
>
> platform_set_drvdata(pdev, bl);
--
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