| Message ID | 20190131132550.26355-1-paul.kocialkowski@bootlin.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/sun4i: tcon: Prepare and enable TCON channel 0 clock at init | expand |
On Thu, Jan 31, 2019 at 02:25:50PM +0100, Paul Kocialkowski wrote: > 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> Applied, thanks! Maxime
diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c index e987615c16f1..b31f5d95cadb 100644 --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c @@ -371,6 +371,7 @@ static int sun4i_tcon_init_clocks(struct device *dev, dev_err(dev, "Couldn't get the TCON channel 0 clock\n"); return PTR_ERR(tcon->sclk0); } + clk_prepare_enable(tcon->sclk0); if (tcon->quirks->has_channel_1) { tcon->sclk1 = devm_clk_get(dev, "tcon-ch1"); @@ -385,6 +386,7 @@ 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); }
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> --- drivers/gpu/drm/sun4i/sun4i_tcon.c | 2 ++ 1 file changed, 2 insertions(+)