[PATCH v3 051/105] drm/vc4: crtc: Add a delay after disabling the PixelValve output

Maxime Ripard maxime at cerno.tech
Wed May 27 15:48:21 UTC 2020

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 at cerno.tech>
 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 b3721bce7c81..dee8dc7b9409 100644
--- a/drivers/gpu/drm/vc4/vc4_crtc.c
+++ b/drivers/gpu/drm/vc4/vc4_crtc.c
@@ -401,6 +401,8 @@ 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);
 	if (vc4_encoder->post_crtc_disable)
git-series 0.9.1

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