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

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

[Frank Zhang]

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

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

[Dmitry Baryshkov]

On Sat, Apr 18, 2026 at 06:19:36PM +0800, 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
> 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);
> +	}

Will audio and audio infoframe remain disabled after consequetive
atomic_enable() call?

>  }
>  
>  static int dw_hdmi_qp_i2c_read(struct dw_hdmi_qp *hdmi,
> -- 
> 2.53.0
> 

-- 
With best wishes
Dmitry

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

[Frank Zhang]

On 4/19/26 08:40, Dmitry Baryshkov wrote:
> On Sat, Apr 18, 2026 at 06:19:36PM +0800, 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
>> 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);
>> +	}
> 
> Will audio and audio infoframe remain disabled after consequetive
> atomic_enable() call?
> 
>>   }
>>   
>>   static int dw_hdmi_qp_i2c_read(struct dw_hdmi_qp *hdmi,
>> -- 
>> 2.53.0
>>
> 

Sorry, I missed clearing the audio infoframe when the PHY is down. The 
next atomic_enable() will write the stale audio infoframe. My mistake.

To clear the stale audio infoframe, dw_hdmi_qp_audio_disable() can 
handle it in the else branch directly, but this seems like a layering 
violation for a bridge driver

I think the better approach is to add a 'reset_audio_infoframe' 
interface in drm_hdmi_state_helper.c that does basically the same as 
drm_atomic_helper_connector_hdmi_clear_audio_infoframe(), but only 
clearing the software state without calling clear_infoframe(). It's also 
a bit odd since it would only be used by dw-hdmi-qp.

I'd like to get the maintainers' opinion about adding such an interface.

Thanks,
Frank Zhang

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

[Dmitry Baryshkov]

On Mon, Apr 20, 2026 at 02:11:28PM +0800, Frank Zhang wrote:
> On 4/19/26 08:40, Dmitry Baryshkov wrote:
> > On Sat, Apr 18, 2026 at 06:19:36PM +0800, 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
> > > 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);
> > > +	}
> > 
> > Will audio and audio infoframe remain disabled after consequetive
> > atomic_enable() call?
> > 
> > >   }
> > >   static int dw_hdmi_qp_i2c_read(struct dw_hdmi_qp *hdmi,
> > > -- 
> > > 2.53.0
> > > 
> > 
> 
> Sorry, I missed clearing the audio infoframe when the PHY is down. The next
> atomic_enable() will write the stale audio infoframe. My mistake.
> 
> To clear the stale audio infoframe, dw_hdmi_qp_audio_disable() can handle it
> in the else branch directly, but this seems like a layering violation for a
> bridge driver
> 
> I think the better approach is to add a 'reset_audio_infoframe' interface in
> drm_hdmi_state_helper.c that does basically the same as
> drm_atomic_helper_connector_hdmi_clear_audio_infoframe(), but only clearing
> the software state without calling clear_infoframe(). It's also a bit odd
> since it would only be used by dw-hdmi-qp.

That sounds too fine-grained and it also will not work straight ahead...

Just for my understanding, let's consider the opposite situation: the
user tries to start audio playback before setting the mode. How is it
handled in the driver?

> 
> I'd like to get the maintainers' opinion about adding such an interface.
> 
> Thanks,
> Frank Zhang
> 

-- 
With best wishes
Dmitry

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

[Detlev Casanova]

Hi Dmitry,

On 4/20/26 05:00, Dmitry Baryshkov wrote:
> On Mon, Apr 20, 2026 at 02:11:28PM +0800, Frank Zhang wrote:
>> On 4/19/26 08:40, Dmitry Baryshkov wrote:
>>> On Sat, Apr 18, 2026 at 06:19:36PM +0800, 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
>>>> 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);
>>>> +	}
>>> Will audio and audio infoframe remain disabled after consequetive
>>> atomic_enable() call?
>>>
>>>>    }
>>>>    static int dw_hdmi_qp_i2c_read(struct dw_hdmi_qp *hdmi,
>>>> -- 
>>>> 2.53.0
>>>>
>> Sorry, I missed clearing the audio infoframe when the PHY is down. The next
>> atomic_enable() will write the stale audio infoframe. My mistake.
>>
>> To clear the stale audio infoframe, dw_hdmi_qp_audio_disable() can handle it
>> in the else branch directly, but this seems like a layering violation for a
>> bridge driver
>>
>> I think the better approach is to add a 'reset_audio_infoframe' interface in
>> drm_hdmi_state_helper.c that does basically the same as
>> drm_atomic_helper_connector_hdmi_clear_audio_infoframe(), but only clearing
>> the software state without calling clear_infoframe(). It's also a bit odd
>> since it would only be used by dw-hdmi-qp.
> That sounds too fine-grained and it also will not work straight ahead...
>
> Just for my understanding, let's consider the opposite situation: the
> user tries to start audio playback before setting the mode. How is it
> handled in the driver?
Currently, when setting audio params, the value of tmds_char_rate is 
needed to
compute some clocks value.

So if the user starts audio before any mode is set, we just return -ENODEV.

I sent a tentative fix to just return 0 some time ago:
https://lore.kernel.org/all/20250722195437.1347865-2-detlev.casanova@collabora.com/

Detlev.
>> I'd like to get the maintainers' opinion about adding such an interface.
>>
>> Thanks,
>> Frank Zhang
>>

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

[Frank Zhang]

On 4/20/26 17:00, Dmitry Baryshkov wrote:
> On Mon, Apr 20, 2026 at 02:11:28PM +0800, Frank Zhang wrote:
>> On 4/19/26 08:40, Dmitry Baryshkov wrote:
>>> On Sat, Apr 18, 2026 at 06:19:36PM +0800, 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
>>>> 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);
>>>> +	}
>>>
>>> Will audio and audio infoframe remain disabled after consequetive
>>> atomic_enable() call?
>>>
>>>>    }
>>>>    static int dw_hdmi_qp_i2c_read(struct dw_hdmi_qp *hdmi,
>>>> -- 
>>>> 2.53.0
>>>>
>>>
>>
>> Sorry, I missed clearing the audio infoframe when the PHY is down. The next
>> atomic_enable() will write the stale audio infoframe. My mistake.
>>
>> To clear the stale audio infoframe, dw_hdmi_qp_audio_disable() can handle it
>> in the else branch directly, but this seems like a layering violation for a
>> bridge driver
>>
>> I think the better approach is to add a 'reset_audio_infoframe' interface in
>> drm_hdmi_state_helper.c that does basically the same as
>> drm_atomic_helper_connector_hdmi_clear_audio_infoframe(), but only clearing
>> the software state without calling clear_infoframe(). It's also a bit odd
>> since it would only be used by dw-hdmi-qp.
> 
> That sounds too fine-grained and it also will not work straight ahead...
> 
> Just for my understanding, let's consider the opposite situation: the
> user tries to start audio playback before setting the mode. How is it
> handled in the driver?
> 

audio_prepare() will return -ENODEV before the mode is set.

I admit modifying dw-hdmi-qp is more reasonable. I have a new approach:

dw-hdmi-qp should have an internal function to clear the audio infoframe 
related registers.
dw_hdmi_qp_bridge_clear_audio_infoframe() should check tmds_char_rate, 
call the new function only when tmds_char_rate is available.
dw_hdmi_qp_bridge_write_audio_infoframe() should call the new function 
directly instead of dw_hdmi_qp_bridge_clear_audio_infoframe(), without 
checking tmds_char_rate.
dw_hdmi_qp_audio_disable() doesn't need any modification.

With this approach, clear_audio_infoframe guards register access by 
checking tmds_char_rate, while write_audio_infoframe does not need to 
check it again. How about it?

Thanks,
Frank Zhang

>>
>> I'd like to get the maintainers' opinion about adding such an interface.
>>
>> Thanks,
>> Frank Zhang
>>
>