On Thu, 29 Oct 2015, Philipp Zabel wrote:
> 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]>
> Reviewed-by: Christian Gmeiner <[email protected]>
> ---
> Changes since v2:
> - Leave GPIO configuration as is (GPIOD_ASIS) when requesting,
> so we can actually check the initial state.
> ---
> drivers/video/backlight/pwm_bl.c | 25 ++++++++++++++++++++++++-
> 1 file changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/video/backlight/pwm_bl.c
> b/drivers/video/backlight/pwm_bl.c
> index ae3c6b6..8e9c261 100644
> --- a/drivers/video/backlight/pwm_bl.c
> +++ b/drivers/video/backlight/pwm_bl.c
> @@ -199,6 +199,8 @@ 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;
> + bool phandle;
> int ret;
>
> if (!data) {
> @@ -242,7 +244,7 @@ static int pwm_backlight_probe(struct platform_device
> *pdev)
> pb->enabled = false;
>
> pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
> - GPIOD_OUT_HIGH);
> + GPIOD_ASIS);
> if (IS_ERR(pb->enable_gpio)) {
> ret = PTR_ERR(pb->enable_gpio);
> goto err_alloc;
> @@ -264,12 +266,32 @@ static int pwm_backlight_probe(struct platform_device
> *pdev)
> pb->enable_gpio = gpio_to_desc(data->enable_gpio);
> }
>
> + phandle = of_find_property(pdev->dev.of_node, "phandle", NULL) != NULL;
This is a little ugly.
If this is the only way to identify the probedness of a device then
you probably want to neaten it up a little. I suggest something along
the lines of:
if (of_find_property(pdev->dev.of_node, "phandle", NULL))
already_probed = true;
Also, do you also want to check for "linux,phandle", as this is always
catered for in drivers/of/*
> + 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 (phandle &&
> + 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)) {
> ret = PTR_ERR(pb->power_supply);
> goto err_alloc;
> }
>
> + if (phandle && !regulator_is_enabled(pb->power_supply))
> + initial_blank = FB_BLANK_POWERDOWN;
> +
> pb->pwm = devm_pwm_get(&pdev->dev, NULL);
> if (IS_ERR(pb->pwm) && PTR_ERR(pb->pwm) != -EPROBE_DEFER
> && !pdev->dev.of_node) {
> @@ -320,6 +342,7 @@ 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);
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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