Re: [PATCH v4] video: simple-panel: add regulator support

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hi,

On 28.01.25 17:06, Michael Grzeschik wrote:

It's good style to write some message here. ;)

> Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
> 
> ---
> v3 -> v4: - better bail out if the regulator is set but not available
> v2 -> v3: - reset regulator->power to NULL in case nothing was found
> v1 -> v2: - added the missing signed-off-by
> ---
>  drivers/video/simple-panel.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/video/simple-panel.c b/drivers/video/simple-panel.c
> index 7048e2f51b..905fd94fb7 100644
> --- a/drivers/video/simple-panel.c
> +++ b/drivers/video/simple-panel.c
> @@ -12,6 +12,7 @@
>  #include <fb.h>
>  #include <gpio.h>
>  #include <of_gpio.h>
> +#include <regulator.h>
>  #include <video/backlight.h>
>  #include <video/vpl.h>
>  #include <i2c/i2c.h>
> @@ -25,6 +26,7 @@ struct simple_panel {
>  	struct device_node *backlight_node;
>  	struct backlight_device *backlight;
>  	struct device_node *ddc_node;
> +	struct regulator *power;
>  	int enable_delay;
>  };
>  
> @@ -49,6 +51,8 @@ static int simple_panel_enable(struct simple_panel *panel)
>  	if (panel->enable_delay)
>  		mdelay(panel->enable_delay);
>  
> +	regulator_enable(panel->power);

Conceptually, you power on a device before you toggle its pins, so this
needs to be moved before the enable_gpio toggling.

> +
>  	if (panel->backlight) {
>  		ret = backlight_set_brightness_default(panel->backlight);
>  		if (ret)
> @@ -65,6 +69,8 @@ static int simple_panel_disable(struct simple_panel *panel)
>  	if (panel->backlight)
>  		backlight_set_brightness(panel->backlight, 0);
>  
> +	regulator_disable(panel->power);

Similarly, this should be after the GPIO was dis-asserted.

> +
>  	if (gpio_is_valid(panel->enable_gpio))
>  		gpio_direction_output(panel->enable_gpio,
>  			!panel->enable_active_high);
> @@ -154,6 +160,12 @@ static int simple_panel_probe(struct device *dev)
>  
>  	panel->backlight_node = of_parse_phandle(node, "backlight", 0);
>  
> +	panel->power = regulator_get(dev, "power");
> +	if (IS_ERR(panel->power)) {
> +		dev_warn(dev, "Cannot find regulator\n");
> +		return PTR_ERR(panel->power);

return dev_errp_probe(dev, panel->power, "Cannot find regulator\n");

So:
   - error code is logged
   - EPROBE_DEFER doesn't result in a diagnostic yet
   - the correct log level is used (warning is for issues that the driver
     can recover from)



> +	}
> +
>  	ret = vpl_register(&panel->vpl);
>  	if (ret)
>  		return ret;


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