drm/vc4: hdmi: Make sure the controller is powered in detect

drm/vc4: hdmi: Make sure the controller is powered in detect

[ Upstream commit 9984d6664ce9dcbbc713962539eaf7636ea246c2 ]

If the HPD GPIO is not available and drm_probe_ddc fails, we end up
reading the HDMI_HOTPLUG register, but the controller might be powered
off resulting in a CPU hang. Make sure we have the power domain and the
HSM clock powered during the detect cycle to prevent the hang from
happening.

Fixes: 4f6e3d66ac52 ("drm/vc4: Add runtime PM support to the HDMI encoder driver")
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210525091059.234116-4-maxime@cerno.tech
Signed-off-by: Sasha Levin <sashal@kernel.org>