On Sat, Nov 16, 2019 at 12:54:19PM +0000, Robin Murphy wrote:

The 0V9 and 1V8 supplies power the PCIe block in the SoC itself, and
are thus fundamental to PCIe being usable at all. As such, it makes
sense to treat them as non-optional and rely on dummy regulators if
not explicitly described.

Reviewed-by: Mark Brown <broonie@kernel.org>

This not only makes sense it's a fix.  regulator_get_optional() should
only be used if the supply may be physically absent (eg, when the
feature can be left unpowered or where there's an option to switch in an
internal regualtor).