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

From: Mark Brown
Date: Wed Dec 01 2021 - 12:02:57 EST


On Wed, Dec 01, 2021 at 05:53:03PM +0100, H. Nikolaus Schaller wrote:
> > Am 01.12.2021 um 16:10 schrieb Mark Brown <broonie@xxxxxxxxxx>:

> > Again, if the supply can be physically absent that is a sensible use
> > case but that means completely absent, not just not software
> > controllable. We can represent fixed voltage regulators just fine.

> The question may be how we can know for a more generic driver that there is always a regulator.
> In the present case we know the schematics but it is just one example.

The datasheet will generally explicitly call out if a supply can be
disconnected. In general it is astonishingly rare for this to be the
case, supporting that case will tend to make designing the chip harder
(you have to cope with what happens where the power domains meet) and
results in whatever functionality the supplies power not working. If
not otherwise specified it's safer to assume that the supplies must be
connected.

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