> -----Original Message----- > From: David Henningsson [mailto:david.henningsson@xxxxxxxxxxxxx] > Sent: Friday, October 23, 2015 6:56 PM > > On 2015-10-23 07:30, Lin, Mengdong wrote: > >> -----Original Message----- > >> From: David Henningsson [mailto:david.henningsson@xxxxxxxxxxxxx] > >> Sent: Thursday, October 22, 2015 4:53 PM > > > > [snip] > > > >> 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.) > > > > Hi David, > > > > Would you please clarify why PA needs such a fixed binding between PCM > 3,7, 8 and pin 0x05,6,7? > > PulseAudio saves information about profile and volume, and does so on > what in PA terminology is called a "port". PA binds this port to a specific Jack > kctl and a PCM device. How this fits together is configured in the files in > /usr/share/pulseaudio/alsa-mixer/ . > > E g, if both one HDMI and one DP monitor are both connected, the user > might set the volume (through PA) of the HDMI monitor to high and the DP > monitor to low. The user then reboots. Now, the PCM-to-monitor (and Jack > kctl-to-monitor) mapping needs to remain the same after a reboot, > otherwise PA might restore the volume to the wrong monitor. I see. Thank you for the info! Random binding can break static mapping since the order of hot-plug unsol events is out of our control. > > > And how will PA handle PCM 9,10 in a different way? > > PA will handle PCM 9 and 10 in the same way. > > > They are not bound to pins, and even not able to dev indexes. > > In practice, a platform will usually support either a DP port or a HDMI port > from the Intel integrated GPU for cost consideration. > > But theoretically i915 can use same device index on two different pins to > connect monitors, e.g. pin 0x05, dev index 2 for one monitor and pin 0x06, > dev index 2 for the other. > > In theory, there are certainly cases where the PCM device allocation can > cause problems for PA. What I'm trying to achieve is that these cases will be > so few that no one will ever notice. I agree. Your suggestion can keep static mapping between monitors and PCM devices during various display mode change and power cycle for common use cases. Regards Mengdong > > > On Intel platforms, the max dev indices is 2. Not sure about Nvidia and > AMD. > > Ok, thanks for the clarification. > > -- > David Henningsson, Canonical Ltd. > https://launchpad.net/~diwic _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
