On 2015-10-22 09:40, Yang, Libin wrote:
From: Raymond Yau [mailto:superquad.vortex2@gmail.com] Sent: Friday, October 16, 2015 8:33 AM To: Takashi Iwai Cc: airlied@linux.ie; tanuk@iki.fi; David Henningsson; Yang, Libin;
Lin,
Mengdong; Girdwood, Liam R; ALSA Development Mailing List Subject: Re: [alsa-devel] DP1.2 MST audio support discussion
>> >> Do it mean that only one DP MST port and no HDMI port on
the
same graphic >> card ? > > No. If there is only one HDMI and one Display Port, this mean that
there
are two pin complexes How about the name of jack detection kctl of three Display Port monitors which are created on the same pin complex but
different
dev_index ?
For the jack name, what do you think if we change to "HDMI/DP, pin=n, dev=m" format? Will it impact on pulseaudio?
Yes, it will impact PulseAudio. It will require changes to files in
http://cgit.freedesktop.org/pulseaudio/pulseaudio/tree/src/modules/
alsa/mixer/paths
So does this mean we should not change the name "HDMI/DP,pcm=3
Jack"
to "HDMI/DP,pin=n, dev=m Jack", otherwise the old PA will not work
with
the new driver?
Yes. And I don't understand why you need to do it, either - if you have three display port monitors on one pin, then they will all get different PCMs (8, 9 and 10), and they will signal their Jack status through "HDMI/DP,pcm=8 Jack", "HDMI/DP,pcm=9 Jack" and "HDMI/DP,pcm=10 Jack".
OK, I see. Thanks. I will not change the jack kctl name. BTW, the PCM number will be the same as converter, which means it will be 3 on Intel platforms.
I'll try to explain my suggestion (which I believe Takashi's buying too) one more time then:
First, when a monitor is plugged in, we need to dynamically assign this monitor to five PCM devices. I believe this scheme will be best:
For a monitor at pin nid 0x05, dev index 0, it will prefer PCM 3. For a monitor at pin nid 0x06, dev index 0, it will prefer PCM 7. For a monitor at pin nid 0x07, dev index 0, it will prefer PCM 8. For a monitor at dev index 1 (any pin), it will prefer PCM 9. For a monitor at dev index 2 (any pin), it will prefer PCM 10.
For monitors at dev indices > 2 (can that happen?), or if the PCM is already assigned to something else, try PCMs in this order: 9, 10, 3, 7, 8. (Subject to discussion perhaps, I don't think the order matters too much, because conflicts will be rare in practice.)
The jack and ELD kctls - one per PCM device - will follow what monitor the PCM is currently assigned to. (kctls belonging to a PCM device that is unassigned will report presence_detect=0 and eld_valid=0.)
Then, at playback open time, a free converter node will be dynamically assigned to the PCM. If there are no free converter nodes, return -EBUSY.
Now remains the case when an unassigned PCM is opened. This needs additional thinking, but the more backwards compatibility we can keep for this case, the better. But I'm not sure about how possible it is to let streams "freewheel" in this new DSP MST world?
Given that my proposed mapping algorithm will never change pin to PCM mapping (unless you have two displayport outputs and use MST on both), I think we can get away with not exposing the actual pin to userspace. And should this later become necessary, we can add a separate kctl for that.
My current thought is to expose the same jack kctls (same number and same name) to userspace while we will create hda_jack_tbl for each device entry. When pcm is bound to the device entry, the corresponding jack kctl will be bound to the device entry.