| From ba6df9ef8edee38252f0d2ef5277c29150a3d4f4 Mon Sep 17 00:00:00 2001 |
| From: Paul Kocialkowski <paul.kocialkowski@bootlin.com> |
| 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 <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 |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/gpu/drm/sun4i/sun4i_tcon.c | 2 ++ |
| 1 file changed, 2 insertions(+) |
| |
| diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c |
| index 3fb084f802e2..8c31c9ab06f8 100644 |
| --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c |
| +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c |
| @@ -672,6 +672,7 @@ 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"); |
| @@ -686,6 +687,7 @@ 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); |
| } |
| |
| -- |
| 2.19.1 |
| |