[PATCH v2] drm/bridge: dw-hdmi-qp: Guard clear_audio_infoframe when PHY is down

[Frank Zhang <rmxpzlb@gmail.com>]

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 disable the PHY.

In this case, dw_hdmi_qp_audio_disable() will call
drm_atomic_helper_connector_hdmi_clear_audio_infoframe() directly,
accessing registers without checking tmds_char_rate.

Move drm_atomic_helper_connector_hdmi_clear_audio_infoframe() inside the
if (hdmi->tmds_char_rate) of dw_hdmi_qp_audio_disable().

Fixes: fd0141d1a8a2 ("drm/bridge: synopsys: Add audio support for dw-hdmi-qp")
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/

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
index d649a1cf07f5..7760527484c8 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
@@ -526,10 +526,10 @@ static void dw_hdmi_qp_audio_disable(struct drm_bridge *bridge,
 {
 	struct dw_hdmi_qp *hdmi = dw_hdmi_qp_from_bridge(bridge);
 
-	drm_atomic_helper_connector_hdmi_clear_audio_infoframe(connector);
-
-	if (hdmi->tmds_char_rate)
+	if (hdmi->tmds_char_rate) {
+		drm_atomic_helper_connector_hdmi_clear_audio_infoframe(connector);
 		dw_hdmi_qp_audio_disable_regs(hdmi);
+	}
 }
 
 static int dw_hdmi_qp_i2c_read(struct dw_hdmi_qp *hdmi,
-- 
2.53.0