Hi Frank,
On 5/12/26 1:31 PM, Frank Zhang wrote:
> The following panic was observed during system reboot:
>
> Kernel panic - not syncing: Asynchronous SError Interrupt
> CPU: 6 UID: 1000 PID: 2348 Comm: pipewire ... 7.0.5+ #4 PREEMPT(full)
> Call trace:
> ...
> regmap_update_bits_base+0x70/0xa8
> dw_hdmi_qp_bridge_clear_audio_infoframe+0x3c/0x58 [dw_hdmi_qp]
> drm_bridge_connector_clear_audio_infoframe+0x2c/0x48 [drm_display_helper]
> ...
> dw_hdmi_qp_audio_disable+0x28/0xa8 [dw_hdmi_qp]
> drm_bridge_connector_audio_shutdown+0x38/0x68 [drm_display_helper]
> drm_connector_hdmi_audio_shutdown+0x28/0x40 [drm_display_helper]
> hdmi_codec_shutdown+0x60/0x90 [snd_soc_hdmi_codec]
> ...
> snd_pcm_release_substream+0xcc/0x120 [snd_pcm]
> snd_pcm_release+0x4c/0xc0 [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: [email protected]
> Signed-off-by: Frank Zhang <[email protected]>
>
> ---
> 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/[email protected]/
>
> 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/[email protected]/
>
> Changes in v4:
> - Update panic stack on 7.0.5
> - Link to v3:
> https://lore.kernel.org/all/[email protected]/
> ---
> drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c | 15 +++++++++------
> 1 file changed, 9 insertions(+), 6 deletions(-)
>
> 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);
Is "avoid the redundant check in the write path" the only reason of open-coding
dw_hdmi_qp_bridge_clear_audio_infoframe()?
Performance wise, I don't think there are any real gains here, so we'd be better
off reusing the existing code where possible.
Regards,
Cristian
