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From:   Maxime Ripard <maxime@cerno.tech>
To:     Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
        Eric Anholt <eric@anholt.net>
Cc:     dri-devel@lists.freedesktop.org,
        linux-rpi-kernel@lists.infradead.org,
        bcm-kernel-feedback-list@broadcom.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Dave Stevenson <dave.stevenson@raspberrypi.com>,
        Tim Gover <tim.gover@raspberrypi.com>,
        Phil Elwell <phil@raspberrypi.com>,
        Maxime Ripard <maxime@cerno.tech>
Subject: [PATCH v4 24/78] drm/vc4: hvs: Make sure our channel is reset
Date:   Wed,  8 Jul 2020 19:41:32 +0200
Message-Id: <1fa32b771828098365162a24654c7bbab805500e.1594230107.git-series.maxime@cerno.tech>
In-Reply-To: <cover.7a1aa1784976093af26cb31fd283cf5b3ed568bb.1594230107.git-series.maxime@cerno.tech>
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In order to clear our intermediate FIFOs that might end up with a stale
pixel, let's make sure our FIFO channel is reset everytime our channel is
setup.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
 drivers/gpu/drm/vc4/vc4_hvs.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/vc4/vc4_hvs.c b/drivers/gpu/drm/vc4/vc4_hvs.c
index c7de77afbf0a..64b9d72471ef 100644
--- a/drivers/gpu/drm/vc4/vc4_hvs.c
+++ b/drivers/gpu/drm/vc4/vc4_hvs.c
@@ -205,6 +205,10 @@ static int vc4_hvs_init_channel(struct vc4_dev *vc4, struct drm_crtc *crtc,
 	u32 dispbkgndx;
 	u32 dispctrl;
 
+	HVS_WRITE(SCALER_DISPCTRLX(chan), 0);
+	HVS_WRITE(SCALER_DISPCTRLX(chan), SCALER_DISPCTRLX_RESET);
+	HVS_WRITE(SCALER_DISPCTRLX(chan), 0);
+
 	/* Turn on the scaler, which will wait for vstart to start
 	 * compositing.
 	 * When feeding the transposer, we should operate in oneshot
-- 
git-series 0.9.1