From 07acb3774e05c578a3839362c2eb3f8077dfb851 Mon Sep 17 00:00:00 2001 From: Paul Kocialkowski Date: Thu, 31 Jan 2019 14:25:50 +0100 Subject: drm/sun4i: tcon: Prepare and enable TCON channel 0 clock at init [ Upstream commit b14e945bda8ae227d1bf2b1837c0c4a61721cd1a ] 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 Signed-off-by: Maxime Ripard Link: https://patchwork.freedesktop.org/patch/msgid/20190131132550.26355-1-paul.kocialkowski@bootlin.com Signed-off-by: Sasha Levin --- drivers/gpu/drm/sun4i/sun4i_tcon.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers/gpu') diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c index f949287d926c..4e0562aa2cc9 100644 --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c @@ -760,6 +760,7 @@ static int sun4i_tcon_init_clocks(struct device *dev, return PTR_ERR(tcon->sclk0); } } + clk_prepare_enable(tcon->sclk0); if (tcon->quirks->has_channel_1) { tcon->sclk1 = devm_clk_get(dev, "tcon-ch1"); @@ -774,6 +775,7 @@ static int sun4i_tcon_init_clocks(struct device *dev, static void sun4i_tcon_free_clocks(struct sun4i_tcon *tcon) { + clk_disable_unprepare(tcon->sclk0); clk_disable_unprepare(tcon->clk); } -- cgit v1.2.3