Sorry to pick up this thread after a long time. > -----Original Message----- > From: daniel.vetter@xxxxxxxx [mailto:daniel.vetter@xxxxxxxx] On Behalf Of > Daniel Vetter > Sent: Thursday, January 23, 2014 4:27 PM > To: Takashi Iwai > On Thu, Jan 23, 2014 at 8:57 AM, Takashi Iwai <tiwai@xxxxxxx> wrote: > >> Thanks for clarification! > >> Maybe we can add output info (eg. display port number) to the eld entries > under /proc/asound/cardx. Is it okay? > > > > It's possible, but the proc file is just a help. It can't be the API. > > For accessing the information, we'll need some new API, or let inform > > via sysfs of the new device. > > Links in sysfs sound like the best approach. drm already has nodes for each > connector, so on the gfx side there's a natural endpoint already. > sysfs links also avoids any naming issues from the start, e.g. the above DP > connector id might lead to clashes with multiple cards. Hi Daniel, Is there a 1:1 mapping between these connector nodes and ports of Gfx display engine? Eg. For Haswell Ultrabook, under /sys/devices/pci0000:00/0000:00:02.0/drm/card0/ There are four connector nodes, card0-DP-1 -> DDI port B card0-eDP-1/ -> DDI port A card0-HDMI-A-1/ -> DDI Port C card0-HDMI-A-2/ -> Which DDI port ? Haswell-ULT does not support port D, and I think port E is for VGA. Hi Takashi, To make user space figure out which audio output is connected to which screen (connector), maybe we can define a new ALSA control for each HDMI/DP PCM device: e.g. numid=x,iface=PCM,name='Screen',device=3 Reading the control will return the name of the DRM connector nodes like ' card0-DP-1'. The audio driver can get the connector name from the gfx driver. For DP1.2 Multi-stream transport, it's not supported by i915 and HD-A driver now. But probably there will be sub-nodes for the DP connector node in the future and an index in their name can be used distinguish monitors connected to the same DP port, like card0-DP-1.1, card0-DP-1.2, card0-DP-1.3 ... These names can be used by the above ALSA PCM 'Screen' control, so we can still know which audio output is to which monitor. Thanks Mengdong _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
