Re: [PATCH v3 3/7] drm: Add driver for Solomon SSD130X OLED displays

[Javier Martinez Canillas <javierm@redhat.com>]

Hello Mark,

Thanks for your feedback.

On 2/9/22 14:43, Mark Brown wrote:
> On Wed, Feb 09, 2022 at 10:03:10AM +0100, Javier Martinez Canillas wrote:
> 
>> +	if (ssd130x->vbat_reg) {
>> +		ret = regulator_enable(ssd130x->vbat_reg);
>> +		if (ret) {
>> +			dev_err(dev, "Failed to enable VBAT: %d\n", ret);
>> +			return ret;
>> +		}
>> +	}
> 
> Unless the device supports power being physically omitted regulator
> usage should not be optional, it's just more code and a recipie for poor
> error handling.

The device has a VCC pin but in most cases this is just connected to a
power provided by the board in its pinout header. For example, I've it
connected to a rpi4 3.3v pin.

I guess in that case what we should do then is to just have a regulator
fixed as the vbat-supply in the Device Tree, that's regulator-always-on.

The old ssd1307fb fbdev driver also had this as optional and I wanted to
keep the new driver as backward compatible. But I understand now that is
not describing the hardware properly by making this regulator optional.

Best regards,
-- 
Javier Martinez Canillas
Linux Engineering
Red Hat