> -----Original Message----- > From: Takashi Iwai [mailto:tiwai@xxxxxxx] > Sent: Wednesday, March 16, 2016 10:28 PM > To: Yang, Libin > Cc: libin.yang@xxxxxxxxxxxxxxx; alsa-devel@xxxxxxxxxxxxxxxx; Lin, > Mengdong > Subject: Re: [PATCH] ALSA: hda - codec add DP MST support > for connection list > > On Wed, 16 Mar 2016 15:24:54 +0100, > Yang, Libin wrote: > > > > > > > -----Original Message----- > > > From: Takashi Iwai [mailto:tiwai@xxxxxxx] > > > Sent: Wednesday, March 16, 2016 10:03 PM > > > To: Yang, Libin > > > Cc: libin.yang@xxxxxxxxxxxxxxx; alsa-devel@xxxxxxxxxxxxxxxx; Lin, > > > Mengdong > > > Subject: Re: [PATCH] ALSA: hda - codec add DP MST > support > > > for connection list > > > > > > On Wed, 16 Mar 2016 14:53:09 +0100, > > > Yang, Libin wrote: > > > > > > > > > > > > > From: Takashi Iwai [mailto:tiwai@xxxxxxx] > > > > > Sent: Wednesday, March 16, 2016 3:56 PM > > > > > To: Yang, Libin > > > > > Cc: libin.yang@xxxxxxxxxxxxxxx; alsa-devel@xxxxxxxxxxxxxxxx; Lin, > > > > > Mengdong > > > > > Subject: Re: [PATCH] ALSA: hda - codec add DP MST > > > support > > > > > for connection list > > > > > > > > > > On Wed, 16 Mar 2016 08:48:58 +0100, > > > > > Yang, Libin wrote: > > > > > > > > > > > > Hi Takashi, > > > > > > > > > > > > > -----Original Message----- > > > > > > > From: Takashi Iwai [mailto:tiwai@xxxxxxx] > > > > > > > Sent: Wednesday, March 16, 2016 3:35 PM > > > > > > > To: libin.yang@xxxxxxxxxxxxxxx > > > > > > > Cc: alsa-devel@xxxxxxxxxxxxxxxx; Yang, Libin; Lin, Mengdong > > > > > > > Subject: Re: [PATCH] ALSA: hda - codec add DP > MST > > > > > support > > > > > > > for connection list > > > > > > > > > > > > > > On Wed, 16 Mar 2016 02:47:31 +0100, > > > > > > > libin.yang@xxxxxxxxxxxxxxx wrote: > > > > > > > > > > > > > > > > From: Libin Yang <libin.yang@xxxxxxxxxxxxxxx> > > > > > > > > > > > > > > > > This patches adds the support of connection list for DP MST. > > > > > > > > With this, hdmi driver in DP MST mode can easily reuse > > > > > > > > the connection list mechanism. > > > > > > > > > > > > > > > > Signed-off-by: Libin Yang <libin.yang@xxxxxxxxxxxxxxx> > > > > > > > > > > > > > > The merge window was already opened, so it's too late for this > > > kind of > > > > > > > change for 4.6, in anyway. > > > > > > > > > > > > That's OK. We can wait for later version. What do you think put > this > > > > > patch > > > > > > and my later patches for MST in the topic branch, such as hdmi- > jack > > > > > brach > > > > > > like before. Later patches for MST needs gfx driver support and > our > > > > > > gfx driver is not ready for it. > > > > > > > > > > > > > > > > > > > > But, the fundamental question: why do we need to manage > the > > > > > cached > > > > > > > list of the widget connection with a device index? In other > words, > > > if > > > > > > > you have a different device index, does the widget connection > > > itself > > > > > > > also change? > > > > > > > > > > > > Based on my test, it should be the same. But from the spec, it > says: > > > > > > > > > > > > 7.3.3.42 Device Select > > > > > > For Digital Display Pin Widget that is multi stream capable, the > > > Device > > > > > Select control determines which > > > > > > Device Entry is currently selected and accessible by the Pin > Widget > > > verbs > > > > > which are controlling the sink > > > > > > device operations. This control verb is only required if it is a > Digital > > > > > Display Pin Widget and multi stream > > > > > > capable. > > > > > > The index is in relation to the Device List associated with the > widget. > > > The > > > > > index is a zero-based offset > > > > > > into the Device List. Once the Device Entry is selected by the Set > > > index, > > > > > all subsequent Pin Widget verbs > > > > > > controlling the sink device operations will be directed to the > selected > > > > > Device Entry, until the Device Select > > > > > > verb get updated with a new value. These Pin Widget verbs > include: > > > > > > Connection Select > > > > > > Get Connection List Entry > > > > > > Amplifier Gain/Mute > > > > > > Power State > > > > > > Pin Widget Control > > > > > > ELD Data > > > > > > DIP-Size > > > > > > DIP-Index > > > > > > DIP-Data > > > > > > DIP-XmitCtrl > > > > > > Content Protection Control > > > > > > ASP Channel Mapping > > > > > > > > > > > > So my understand is this may be changed. > > > > > > > > > > But the pin widget is the terminal. So, if you have a device index to > > > > > choose a device there, the widget connection list itself doesn't > > > > > change. Or am I missing anything? > > > > > > > > The pin may connect to several converters (for example), and it > > > > can choose which converter to use. And from the spec, it seems > > > > each device entry can have different connection list entry. > > > > However from my test, all device entries on the same pin will have > > > > the same list. > > > > > > Hrm, OK, so it makes sense to keep the list. OTOH, it means that the > > > connection list may change endlessly depending on the device index. > > > And, we likely need to clean up the connection list at unplug. > > > > I'm not sure whether the connection list will be changed when unplug. > > Suppose it should be the capability and will not change? > > How can we know? Hardware designers have often a too creative mind :) We should take care of it :) Regards, Libin > > > Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
