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

[Detlev Casanova <detlev.casanova@collabora.com>]

Hi Frank,

Please add me to CC if you send a v2.

On 4/16/26 05:31, Frank Zhang wrote:
> 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
> clear_audio_infoframe(), accessing registers without checking
> tmds_char_rate.
>
> Add a tmds_char_rate check in dw_hdmi_qp_bridge_clear_audio_infoframe()
> to skip the register write when the PHY is inactive.
>
> Signed-off-by: Frank Zhang <rmxpzlb@gmail.com>
Add a "Fixes:" tag so this gets backported were needed.
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
> index d649a1cf07f5..f963dff81dc6 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
> @@ -886,11 +886,12 @@ 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)
I'd rather move the call to 
drm_atomic_helper_connector_hdmi_clear_audio_infoframe() inside the if 
(hdmi->tmds_char_rate) of dw_hdmi_qp_audio_disable().
There is no need to check for tmds_char_rate in every 
dw_hdmi_qp_bridge_clear_audio_infoframe() call.
> +		dw_hdmi_qp_mod(hdmi, 0,
> +			       PKTSCHED_ACR_TX_EN |
> +			       PKTSCHED_AUDS_TX_EN |
> +			       PKTSCHED_AUDI_TX_EN,
> +			       PKTSCHED_PKT_EN);
>   
>   	return 0;
>   }

Regards,
Detlev.