On Tue, 22 Nov 2016, Peter Ujfalusi wrote:
> Move the checks to select the initial state for the backlight to a new
> function and document the checks we are doing.
>
> With the separate function it is going to be easier to fix or improve the
> initial power state configuration later and it is easier to read the code.
>
> Signed-off-by: Peter Ujfalusi <peter.ujfal...@ti.com>
> Reviewed-by: Philipp Zabel <p.za...@pengutronix.de>
> Reviewed-by: Thierry Reding <tred...@nvidia.com>
> ---
> drivers/video/backlight/pwm_bl.c | 56
> ++++++++++++++++++++++++++--------------
> 1 file changed, 37 insertions(+), 19 deletions(-)
Applied for v4.11, thanks.
> diff --git a/drivers/video/backlight/pwm_bl.c
> b/drivers/video/backlight/pwm_bl.c
> index 12614006211e..5712ddd053dd 100644
> --- a/drivers/video/backlight/pwm_bl.c
> +++ b/drivers/video/backlight/pwm_bl.c
> @@ -192,6 +192,32 @@ static int pwm_backlight_parse_dt(struct device *dev,
> }
> #endif
>
> +static int pwm_backlight_initial_power_state(const struct pwm_bl_data *pb)
> +{
> + struct device_node *node = pb->dev->of_node;
> +
> + /* Not booted with device tree or no phandle link to the node */
> + if (!node || !node->phandle)
> + return FB_BLANK_UNBLANK;
> +
> + /*
> + * 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 the enable GPIO is disabled, do not enable the backlight */
> + if (pb->enable_gpio && gpiod_get_value(pb->enable_gpio) == 0)
> + return FB_BLANK_POWERDOWN;
> +
> + /* The regulator is disabled, do not enable the backlight */
> + if (!regulator_is_enabled(pb->power_supply))
> + return FB_BLANK_POWERDOWN;
> +
> + return FB_BLANK_UNBLANK;
> +}
> +
> static int pwm_backlight_probe(struct platform_device *pdev)
> {
> struct platform_pwm_backlight_data *data = dev_get_platdata(&pdev->dev);
> @@ -200,7 +226,6 @@ static int pwm_backlight_probe(struct platform_device
> *pdev)
> struct backlight_device *bl;
> struct device_node *node = pdev->dev.of_node;
> struct pwm_bl_data *pb;
> - int initial_blank = FB_BLANK_UNBLANK;
> struct pwm_args pargs;
> int ret;
>
> @@ -267,20 +292,16 @@ static int pwm_backlight_probe(struct platform_device
> *pdev)
> pb->enable_gpio = gpio_to_desc(data->enable_gpio);
> }
>
> - 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 (node && node->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);
> - }
> + /*
> + * If the GPIO is configured as input, 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_direction_output(pb->enable_gpio, 1);
>
> pb->power_supply = devm_regulator_get(&pdev->dev, "power");
> if (IS_ERR(pb->power_supply)) {
> @@ -288,9 +309,6 @@ static int pwm_backlight_probe(struct platform_device
> *pdev)
> goto err_alloc;
> }
>
> - if (node && node->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 && !node) {
> dev_err(&pdev->dev, "unable to request PWM, trying legacy
> API\n");
> @@ -347,7 +365,7 @@ static int pwm_backlight_probe(struct platform_device
> *pdev)
> }
>
> bl->props.brightness = data->dft_brightness;
> - bl->props.power = initial_blank;
> + bl->props.power = pwm_backlight_initial_power_state(pb);
> 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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