Re: [PATCH v2 3/3] fbdev: omap2: panel-dpi: implement support for a vcc regulator

["Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>]

Hello,

Cc += Liam Girdwood, Mark Brown

On Fri, Feb 26, 2016 at 12:13:07PM +0200, Tomi Valkeinen wrote:
> On 16/02/16 15:48, Uwe Kleine-König wrote:
> > Hello Tomi,
> > 
> > On Tue, Feb 16, 2016 at 03:00:00PM +0200, Tomi Valkeinen wrote:
> >> On 20/12/15 13:13, Uwe Kleine-König wrote:
> >>> @@ -223,6 +232,10 @@ static int panel_dpi_probe_of(struct platform_device *pdev)
> >>>  	if (IS_ERR(gpio))
> >>>  		return PTR_ERR(gpio);
> >>>  
> >>> +	ddata->vcc_supply = devm_regulator_get(&pdev->dev, "vcc");
> >>> +	if (IS_ERR(ddata->vcc_supply))
> >>> +		return PTR_ERR(ddata->vcc_supply);
> >>
> >> devm_regulator_get_optional()?
> > 
> > That would make the specification of a vcc supply obligatory IIUC. (Yes,
> > the semantic difference between regulator_get vs. regulator_get_optional
> > is reversed when comparing to gpio_get vs. gpio_get_optional.)
> 
> This is a bit confusing...
> 
> So, is regulator_get_optional() meant for cases where the device can
> truly function without the supply in question? And regulator_get()
> should be used when the device needs the supply, even if the supply
> cannot be controlled via SW, and thus we may not even have the supply
> visible in the SW side (leading to using dummy regulator)?

Yeah, I think this is the right picture.

Best regards
Uwe

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