[PATCH 08/11] drm/vc4: hdmi: Remove firmware logic for MAI threshold setting

[Maxime Ripard]

From: Dom Cobley <popcornmix at gmail.com>

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 at gmail.com>
Signed-off-by: Maxime Ripard <maxime at cerno.tech>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 22 ++++++----------------
 1 file changed, 6 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index f74a6b99d4ec..505574e6cfd3 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -1213,22 +1213,12 @@ static int vc4_hdmi_audio_hw_params(struct snd_pcm_substream *substream,
 	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 |
-- 
2.31.1