[alsa-devel] [PATCH v2] ASoC: hdac_hdmi: Program pin-port-mux during jack report event

[Sriram Periyasamy]

On Wed, Jul 11, 2018 at 08:45:05AM +0200, Takashi Iwai wrote:
> On Wed, 11 Jul 2018 08:30:43 +0200,
> Sriram Periyasamy wrote:
> > 
> > @@ -167,6 +171,30 @@ static void hdac_hdmi_jack_report(struct hdac_hdmi_pcm *pcm,
> >  
> >  	if (is_connect) {
> >  		/*
> > +		 * Increment the usage count to ensure that the device
> > +		 * is runtime active to send verb across.
> > +		 */
> > +		pm_runtime_get_sync(&edev->hdev.dev);
> 
> This looks more reasonable now, but...
> 
> > +		/* set the device if pin is mst_capable */
> > +		if (hdac_hdmi_port_select_set(edev, port) < 0) {
> > +			dev_err(&edev->hdev.dev,
> > +				"port %d device select fail\n", port->id);
> > +			return;
> 
> It appears like an unbalanced pm refcount here in the error path.
> 

Thanks for pointing out. Will fix it.

> > +		}
> > +
> > +		/*
> > +		 * Restore the connection selection index of the
> > +		 * respective pin.
> > +		 */
> > +		if (port->pin->conn_index > 0)
> > +			snd_hdac_codec_write(&edev->hdev, port->pin->nid,
> > +						0, AC_VERB_SET_CONNECT_SEL,
> > +						port->pin->conn_index - 1);
> 
> And, here checks conn_index > 0 while...
> 
> > @@ -903,6 +931,9 @@ static int hdac_hdmi_set_pin_port_mux(struct snd_kcontrol *kcontrol,
> >  		}
> >  	}
> >  
> > +	if (ucontrol->value.enumerated.item[0] > 0)
> > +		port->pin->conn_index =	ucontrol->value.enumerated.item[0];
> 
> ... conn_index is set only non-zero here.
> 
> That is, once after a non-zero is passed, conn_index can't any longer
> back to zero.  I guess it's not intentional?
> 

No, it is intentional. For example, two ports are connected to the
display and user land set mux only for one port. Hence other port's
conn_index is set to default 0. When jack report happens for that port,
we would be writing invalid connection select index which will lead to
undefined hardware behaviour as per the HDA spec.

Though it is userland's mistake, it is better to take care in the driver.

Thanks,
Sriram.