[PATCH 08/31] drm/vc4: hdmi: Increase audio MAI fifo dreq threshold

[Dave Stevenson]

From: Dom Cobley <popcornmix at gmail.com>

Now we wait for write responses and have a burst
size of 4, we can set the fifo threshold much higher.

Set it to 28 (of the 32 entry size) to keep fifo
fuller and reduce chance of underflow.

Signed-off-by: Dom Cobley <popcornmix at gmail.com>
Signed-off-by: Dave Stevenson <dave.stevenson at raspberrypi.com>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index afeeff660fa5..21046056f63d 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -2046,6 +2046,7 @@ static int vc4_hdmi_audio_prepare(struct device *dev, void *data,
 	struct vc4_hdmi *vc4_hdmi = dev_get_drvdata(dev);
 	struct drm_device *drm = vc4_hdmi->connector.dev;
 	struct drm_connector *connector = &vc4_hdmi->connector;
+	struct vc4_dev *vc4 = to_vc4_dev(drm);
 	unsigned int sample_rate = params->sample_rate;
 	unsigned int channels = params->channels;
 	unsigned long flags;
@@ -2103,11 +2104,18 @@ static int vc4_hdmi_audio_prepare(struct device *dev, void *data,
 					     VC4_HDMI_AUDIO_PACKET_CEA_MASK);
 
 	/* Set the MAI threshold */
-	HDMI_WRITE(HDMI_MAI_THR,
-		   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));
+	if (vc4->is_vc5)
+		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(0x1c, VC4_HD_MAI_THR_DREQHIGH) |
+			   VC4_SET_FIELD(0x1c, VC4_HD_MAI_THR_DREQLOW));
+	else
+		HDMI_WRITE(HDMI_MAI_THR,
+			   VC4_SET_FIELD(0x8, VC4_HD_MAI_THR_PANICHIGH) |
+			   VC4_SET_FIELD(0x8, VC4_HD_MAI_THR_PANICLOW) |
+			   VC4_SET_FIELD(0x6, VC4_HD_MAI_THR_DREQHIGH) |
+			   VC4_SET_FIELD(0x8, VC4_HD_MAI_THR_DREQLOW));
 
 	HDMI_WRITE(HDMI_MAI_CONFIG,
 		   VC4_HDMI_MAI_CONFIG_BIT_REVERSE |
-- 
2.34.1