[PATCH v7 04/23] drm: bridge: dw_hdmi: Hold bridge ref until connector cleanup

[Jonas Karlman]

Hello Luca,

On 5/19/2026 2:06 PM, Luca Ceresoli wrote:
> On Mon, 18 May 2026 18:01:40 +0000, Jonas Karlman <jonas at kwiboo.se> wrote:
> 
> Hello Jonas,
> 
>>
>> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> index b7bfc0e9a6b2..9d795c550f8a 100644
>> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> @@ -2600,10 +2609,14 @@ static int dw_hdmi_connector_create(struct dw_hdmi *hdmi)
>>  
>>  	drm_connector_helper_add(connector, &dw_hdmi_connector_helper_funcs);
>>  
>> -	drm_connector_init_with_ddc(hdmi->bridge.dev, connector,
>> -				    &dw_hdmi_connector_funcs,
>> -				    DRM_MODE_CONNECTOR_HDMIA,
>> -				    hdmi->ddc);
>> +	ret = drm_connector_init_with_ddc(hdmi->bridge.dev, connector,
>> +					  &dw_hdmi_connector_funcs,
>> +					  DRM_MODE_CONNECTOR_HDMIA,
>> +					  hdmi->ddc);
>> +	if (ret)
>> +		return ret;
>> +
>> +	drm_bridge_get(&hdmi->bridge);
> 
> I'm not fully following the code paths, but both the report and the fix
> make sense to me. Only I'd move the drm_bridge_get() before
> drm_connector_init_with_ddc(), to avoid a short window where no reference
> is held and the bridge might be destroyed before drm_bridge_get() is
> called. I'm not sure this can happen, but it's better to write the code in
> a way that clearly makes it impossible.

dw_hdmi_connector_create() is only called from dw_hdmi_bridge_attach()
so the bridge should already have a ref for the lifetime of this call.

I explicitly chose the placement after drm_connector_init_with_ddc()
to ensure ref count is correctly balanced without having to add a
drm_bridge_put() call in any error path. I.e. connector destroy() is
only called when drm_connector_init_with_ddc() succeeds.

This code/call is also planned to be removed in a future series, so I do
not think moving drm_bridge_get() is necessary unless you think we need
to protect against possible bad behavior from DRM core?

Regards,
Jonas

> 
> Otherwise looks good.
> 
> Luca
>