Re: [PATCH v10 4/8] drm/ingenic: Add dw-hdmi driver for jz4780

["H. Nikolaus Schaller" <hns@goldelico.com>]

Hi,

> Am 01.12.2021 um 14:39 schrieb Mark Brown <broonie@kernel.org>:
> 
> On Wed, Dec 01, 2021 at 01:02:45PM +0000, Paul Cercueil wrote:
>> Le mar., nov. 30 2021 at 22:26:37 +0100, H. Nikolaus Schaller
> 
>>> +	regulator = devm_regulator_get_optional(&pdev->dev, "hdmi-5v");
>>> +	if (IS_ERR(regulator)) {
>>> +		ret = PTR_ERR(regulator);
> 
> Why is this using _optional()?  This should only be done when the supply
> can be physically absent

There can be +5V for HDMI but without a regulator that is visible to or controllable
by the driver.

So hdmi-5v can be simply missing in DTS in which case the driver does not need to
care about. The driver just can't turn it on or off.

> (in which case I'd expect to see special
> handling).

The special case is to not enable/disable the regulator if it does not exist
and assume that there is hardware providing it otherwise (the driver can't know
that except by using get_optional). This is done by the code below

>>> +	if (IS_ERR(regulator)) {

...

> +	if (!regulator)
> +		return 0;
> 
> +	ret = regulator_enable(regulator);

...

BR and thanks,
Nikolaus