linux-kernel - [PATCH 5.10 199/545] drm/vc4: hdmi: Remove firmware logic for MAI threshold setting

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Message-Id: <20220819153838.285646925@linuxfoundation.org>
Date:   Fri, 19 Aug 2022 17:39:29 +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 5.10 199/545] drm/vc4: hdmi: Remove firmware logic for MAI threshold setting

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

[ Upstream commit 8434111ccfec8fc0549ec325a632067232d38e14 ]

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@...il.com>
Signed-off-by: Maxime Ripard <maxime@...no.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20210525132354.297468-10-maxime@cerno.tech
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 d5822878b5a7..6acc34f1e095 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -1031,22 +1031,12 @@ 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 |
-- 
2.35.1