linux-kernel - [PATCH 5.19 0417/1157] drm/vc4: hdmi: Avoid full hdmi audio fifo writes

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Date:   Mon, 15 Aug 2022 19:56:13 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dom Cobley <popcornmix@...il.com>,
        Maxime Ripard <maxime@...no.tech>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.19 0417/1157] drm/vc4: hdmi: Avoid full hdmi audio fifo writes

From: Dom Cobley <popcornmix@...il.com>

[ Upstream commit 1c594eeccf92368177c2e22f1d3ee4933dfb8567 ]

We are getting occasional VC4_HD_MAI_CTL_ERRORF in
HDMI_MAI_CTL which seem to correspond with audio dropouts.

Reduce the threshold where we deassert DREQ to avoid the fifo
overfilling

Fixes: bb7d78568814 ("drm/vc4: Add HDMI audio support")
Signed-off-by: Dom Cobley <popcornmix@...il.com>
Link: https://lore.kernel.org/r/20220613144800.326124-21-maxime@cerno.tech
Signed-off-by: Maxime Ripard <maxime@...no.tech>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index ecd49214bd92..d0921f832f19 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -1956,10 +1956,10 @@ static int vc4_hdmi_audio_prepare(struct device *dev, void *data,
 
 	/* Set the MAI threshold */
 	HDMI_WRITE(HDMI_MAI_THR,
-		   VC4_SET_FIELD(0x10, VC4_HD_MAI_THR_PANICHIGH) |
-		   VC4_SET_FIELD(0x10, VC4_HD_MAI_THR_PANICLOW) |
-		   VC4_SET_FIELD(0x10, VC4_HD_MAI_THR_DREQHIGH) |
-		   VC4_SET_FIELD(0x10, VC4_HD_MAI_THR_DREQLOW));
+		   VC4_SET_FIELD(0x08, VC4_HD_MAI_THR_PANICHIGH) |
+		   VC4_SET_FIELD(0x08, VC4_HD_MAI_THR_PANICLOW) |
+		   VC4_SET_FIELD(0x06, VC4_HD_MAI_THR_DREQHIGH) |
+		   VC4_SET_FIELD(0x08, VC4_HD_MAI_THR_DREQLOW));
 
 	HDMI_WRITE(HDMI_MAI_CONFIG,
 		   VC4_HDMI_MAI_CONFIG_BIT_REVERSE |
-- 
2.35.1