drm/sun4i: tcon: Prepare and enable TCON channel 0 clock at init
authorPaul Kocialkowski <paul.kocialkowski@bootlin.com>
Thu, 31 Jan 2019 13:25:50 +0000 (14:25 +0100)
committerMaxime Ripard <maxime.ripard@bootlin.com>
Fri, 1 Feb 2019 13:10:51 +0000 (14:10 +0100)
commitb14e945bda8ae227d1bf2b1837c0c4a61721cd1a
tree85adcfffe7431279aa217c24baf4b9da8a2f5115
parent053ff09f1a8f2151339f9fda457c5250929d1c49
drm/sun4i: tcon: Prepare and enable TCON channel 0 clock at init

When initializing clocks, a reference to the TCON channel 0 clock is
obtained. However, the clock is never prepared and enabled later.
Switching from simplefb to DRM actually disables the clock (that was
usually configured by U-Boot) because of that.

On the V3s, this results in a hang when writing to some mixer registers
when switching over to DRM from simplefb.

Fix this by preparing and enabling the clock when initializing other
clocks. Waiting for sun4i_tcon_channel_enable to enable the clock is
apparently too late and results in the same mixer register access hang.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190131132550.26355-1-paul.kocialkowski@bootlin.com
drivers/gpu/drm/sun4i/sun4i_tcon.c