1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
|
From 5f22fca663178a49bbb72058ea9225d35b3d155d Mon Sep 17 00:00:00 2001
From: Dom Cobley <popcornmix@gmail.com>
Date: Thu, 25 Jun 2020 18:48:40 +0100
Subject: [PATCH] vc4_hdmi: Remove firmware logic for MAI threshold
setting
This was a workaround for bugs in hardware on earlier Pi models
and wasn't totally successful.
It makes audio quality worse on a Pi4 at the higher sample rates
Signed-off-by: Dom Cobley <popcornmix@gmail.com>
---
drivers/gpu/drm/vc4/vc4_hdmi.c | 22 ++++++----------------
1 file changed, 6 insertions(+), 16 deletions(-)
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -1010,22 +1010,12 @@ static int vc4_hdmi_audio_prepare(struct
audio_packet_config |= VC4_SET_FIELD(channel_mask,
VC4_HDMI_AUDIO_PACKET_CEA_MASK);
- /* Set the MAI threshold. This logic mimics the firmware's. */
- if (vc4_hdmi->audio.samplerate > 96000) {
- HDMI_WRITE(HDMI_MAI_THR,
- VC4_SET_FIELD(0x12, VC4_HD_MAI_THR_DREQHIGH) |
- VC4_SET_FIELD(0x12, VC4_HD_MAI_THR_DREQLOW));
- } else if (vc4_hdmi->audio.samplerate > 48000) {
- HDMI_WRITE(HDMI_MAI_THR,
- VC4_SET_FIELD(0x14, VC4_HD_MAI_THR_DREQHIGH) |
- VC4_SET_FIELD(0x12, VC4_HD_MAI_THR_DREQLOW));
- } else {
- 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));
- }
+ /* 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));
HDMI_WRITE(HDMI_MAI_CONFIG,
VC4_HDMI_MAI_CONFIG_BIT_REVERSE |
|
