linux-kernel - [PATCH AUTOSEL 5.14 009/252] drm: vc4: Fix pixel-wrap issue with DVP teardown

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Date:   Thu,  9 Sep 2021 07:37:03 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Tim Gover <tim.gover@...pberrypi.com>,
        Maxime Ripard <maxime@...no.tech>,
        Sasha Levin <sashal@...nel.org>,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 5.14 009/252] drm: vc4: Fix pixel-wrap issue with DVP teardown

From: Tim Gover <tim.gover@...pberrypi.com>

[ Upstream commit 0b066a6809d0f8fd9868e383add36aa5a2fa409d ]

Adjust the DVP enable/disable sequence to avoid a pixel getting stuck
in an internal, non resettable FIFO within PixelValve when changing
HDMI resolution.

The blank pixels features of the DVP can prevent signals back to
pixelvalve causing it to not clear the FIFO. Adjust the ordering
and timing of operations to ensure the clear signal makes it through to
pixelvalve.

Signed-off-by: Tim Gover <tim.gover@...pberrypi.com>
Signed-off-by: Maxime Ripard <maxime@...no.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20210628130533.144617-1-maxime@cerno.tech
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index ad92dbb128b3..f91d37beb113 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -613,12 +613,12 @@ static void vc4_hdmi_encoder_post_crtc_disable(struct drm_encoder *encoder,
 
 	HDMI_WRITE(HDMI_RAM_PACKET_CONFIG, 0);
 
-	HDMI_WRITE(HDMI_VID_CTL, HDMI_READ(HDMI_VID_CTL) |
-		   VC4_HD_VID_CTL_CLRRGB | VC4_HD_VID_CTL_CLRSYNC);
+	HDMI_WRITE(HDMI_VID_CTL, HDMI_READ(HDMI_VID_CTL) | VC4_HD_VID_CTL_CLRRGB);
 
-	HDMI_WRITE(HDMI_VID_CTL,
-		   HDMI_READ(HDMI_VID_CTL) | VC4_HD_VID_CTL_BLANKPIX);
+	mdelay(1);
 
+	HDMI_WRITE(HDMI_VID_CTL,
+		   HDMI_READ(HDMI_VID_CTL) & ~VC4_HD_VID_CTL_ENABLE);
 	vc4_hdmi_disable_scrambling(encoder);
 }
 
@@ -628,12 +628,12 @@ static void vc4_hdmi_encoder_post_crtc_powerdown(struct drm_encoder *encoder,
 	struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
 	int ret;
 
+	HDMI_WRITE(HDMI_VID_CTL,
+		   HDMI_READ(HDMI_VID_CTL) | VC4_HD_VID_CTL_BLANKPIX);
+
 	if (vc4_hdmi->variant->phy_disable)
 		vc4_hdmi->variant->phy_disable(vc4_hdmi);
 
-	HDMI_WRITE(HDMI_VID_CTL,
-		   HDMI_READ(HDMI_VID_CTL) & ~VC4_HD_VID_CTL_ENABLE);
-
 	clk_disable_unprepare(vc4_hdmi->pixel_bvb_clock);
 	clk_disable_unprepare(vc4_hdmi->pixel_clock);
 
@@ -1015,6 +1015,7 @@ static void vc4_hdmi_encoder_post_crtc_enable(struct drm_encoder *encoder,
 
 	HDMI_WRITE(HDMI_VID_CTL,
 		   VC4_HD_VID_CTL_ENABLE |
+		   VC4_HD_VID_CTL_CLRRGB |
 		   VC4_HD_VID_CTL_UNDERFLOW_ENABLE |
 		   VC4_HD_VID_CTL_FRAME_COUNTER_RESET |
 		   (vsync_pos ? 0 : VC4_HD_VID_CTL_VSYNC_LOW) |
-- 
2.30.2