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

[Michael Grzeschik <mgr@pengutronix.de>]

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On Tue, Jan 28, 2025 at 05:49:56PM +0100, Ahmad Fatoum wrote:
>Hi,
>
>On 28.01.25 17:06, Michael Grzeschik wrote:
>
>It's good style to write some message here. ;)

Right, but I skipped it for v5. sorry. :)

>> 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.

This is true for both cases. I fixed that.

>
>> +
>>  	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)

Great hint. Did that in v5.

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

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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