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linux (RPi): add patch to avoid full hdmi audio fifo writes on vc4

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Signed-off-by: Matthias Reichl <hias@horus.com>
This commit is contained in:
Matthias Reichl 2021-02-16 16:45:26 +01:00
parent 2700647f48
commit 0d615b9ec6
1 changed files with 30 additions and 0 deletions
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30
packages/linux/patches/raspberrypi/linux-011-vc4-Avoid-full-hdmi-audio-fifo-writes.patch Normal file
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@ -0,0 +1,30 @@
From 6ddb85813f7a61637a54f76a76ccb95ade8a50de Mon Sep 17 00:00:00 2001
From: Dom Cobley <popcornmix@gmail.com>
Date: Sun, 24 Jan 2021 15:44:10 +0000
Subject: [PATCH] vc4: Avoid full hdmi audio fifo writes
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
---
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 64b1567998861..3b85158fbbaa8 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -1562,10 +1562,10 @@ static int vc4_hdmi_audio_prepare(struct snd_pcm_substream *substream,
/* 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(0x08, 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 |