Hi, On Wed, Jul 29, 2020 at 03:09:21PM +0100, Dave Stevenson wrote: > On Wed, 8 Jul 2020 at 18:43, Maxime Ripard <maxime@xxxxxxxxxx> wrote: > > > > In order to avoid pixels getting stuck in the (unflushable) FIFO between > > the HVS and the PV, we need to add some delay after disabling the PV output > > and before disabling the HDMI controller. 20ms seems to be good enough so > > let's use that. > > > > Signed-off-by: Maxime Ripard <maxime@xxxxxxxxxx> > > --- > > drivers/gpu/drm/vc4/vc4_crtc.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/drivers/gpu/drm/vc4/vc4_crtc.c b/drivers/gpu/drm/vc4/vc4_crtc.c > > index d0b326e1df0a..7b178d67187f 100644 > > --- a/drivers/gpu/drm/vc4/vc4_crtc.c > > +++ b/drivers/gpu/drm/vc4/vc4_crtc.c > > @@ -403,6 +403,8 @@ static void vc4_crtc_atomic_disable(struct drm_crtc *crtc, > > ret = wait_for(!(CRTC_READ(PV_V_CONTROL) & PV_VCONTROL_VIDEN), 1); > > WARN_ONCE(ret, "Timeout waiting for !PV_VCONTROL_VIDEN\n"); > > > > + mdelay(20); > > mdelay for 20ms seems a touch unfriendly as it's a busy wait. Can we > not msleep instead? Since the timing was fairly critical, sleeping didn't seem like a good solution since there's definitely some chance you overshoot and end up with a higher time than the one you targeted. Maxime
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