[PATCH v3] drm/bridge: dw-hdmi-qp: Guard clear_audio_infoframe when PHY is down

Frank Zhang
2026-04-23T08:15:32Z

The following panic was observed during system reboot:

Kernel panic - not syncing: Asynchronous SError Interrupt
CPU: 7 UID: 1000 PID: 2637 Comm: pipewire ... 6.19.10-300.fc44.aarch64
Call trace:
...
regmap_update_bits_base+0x5c/0x90
dw_hdmi_qp_bridge_clear_infoframe+0xb0/0x120 [dw_hdmi_qp]
drm_bridge_connector_clear_infoframe+0x28/0x48 [drm_display_helper]
...
dw_hdmi_qp_audio_disable+0x24/0xb8 [dw_hdmi_qp]
drm_bridge_connector_audio_shutdown+0x30/0x60 [drm_display_helper]
drm_connector_hdmi_audio_shutdown+0x24/0x38 [drm_display_helper]
hdmi_codec_shutdown+0x60/0x90 [snd_soc_hdmi_codec]
...
snd_pcm_release_substream.part.0+0x44/0xd8 [snd_pcm]
snd_pcm_release+0x60/0xe8 [snd_pcm]
...

The root cause is pipewire tries to close the HDMI audio device after
atomic_disable(), which sets tmds_char_rate to 0 and disables the PHY.

In this case, dw_hdmi_qp_audio_disable() will call
dw_hdmi_qp_bridge_clear_audio_infoframe(), accessing register without
checking tmds_char_rate.

Add a tmds_char_rate guard in dw_hdmi_qp_bridge_clear_audio_infoframe().
Decouple write_audio_infoframe from clear_audio_infoframe to avoid the
redundant check in the write path.
Add PKTSCHED_AMD_TX_EN to the clear mask to keep the enable/disable
balance.

Fixes: fd0141d1a8a2 ("drm/bridge: synopsys: Add audio support for dw-hdmi-qp")
Cc: stable@vger.kernel.org
Signed-off-by: Frank Zhang <rmxpzlb@gmail.com>

---
Changes in v2:
- Move drm_atomic_helper_connector_hdmi_clear_audio_infoframe() inside
the if (hdmi->tmds_char_rate) of dw_hdmi_qp_audio_disable().
- Link to v1: https://lore.kernel.org/all/20260416093150.13853-1-rmxpzlb@gmail.com/

Changes in v3:
- Add a tmds_char_rate guard in clear_audio_infoframe path.
- Decouple write_audio_infoframe from clear_audio_infoframe.
- Balance the PKTSCHED_AMD_TX_EN bit enable/disable.
- Link to v2: https://lore.kernel.org/all/20260418101936.7731-1-rmxpzlb@gmail.com/

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
index d649a1cf07f5..1c18f8650fcd 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
@@ -886,11 +886,11 @@ static int dw_hdmi_qp_bridge_clear_audio_infoframe(struct drm_bridge *bridge)
{
struct dw_hdmi_qp *hdmi = bridge->driver_private;

- dw_hdmi_qp_mod(hdmi, 0,
- PKTSCHED_ACR_TX_EN |
- PKTSCHED_AUDS_TX_EN |
- PKTSCHED_AUDI_TX_EN,
- PKTSCHED_PKT_EN);
+ if (hdmi->tmds_char_rate)
+ dw_hdmi_qp_mod(hdmi, 0,
+ PKTSCHED_ACR_TX_EN | PKTSCHED_AMD_TX_EN |
+ PKTSCHED_AUDS_TX_EN | PKTSCHED_AUDI_TX_EN,
+ PKTSCHED_PKT_EN);

return 0;
}
@@ -989,7 +989,10 @@ static int dw_hdmi_qp_bridge_write_audio_infoframe(struct drm_bridge *bridge,
{
struct dw_hdmi_qp *hdmi = bridge->driver_private;

- dw_hdmi_qp_bridge_clear_audio_infoframe(bridge);
+ dw_hdmi_qp_mod(hdmi, 0,
+ PKTSCHED_ACR_TX_EN | PKTSCHED_AMD_TX_EN |
+ PKTSCHED_AUDS_TX_EN | PKTSCHED_AUDI_TX_EN,
+ PKTSCHED_PKT_EN);

/*
* AUDI_CONTENTS0: { RSV, HB2, HB1, RSV }
--
2.53.0