On Tue, Feb 18, 2014 at 01:58:22PM +0000, Lin, Mengdong wrote: > 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. There's no fixed mapping with the port and the connector name. The number in the connector name is basically just a running number per connector type. However I do believe we do register the connectors in the order of the ports more or less always, so you can *sometimes* deduce the port name from the connector. I suppose in this example HDMI-A-1 is port B, HDMI-A-2 is port C, and DP-1 can be either port B or port C. DP++ is the reason why we have overlapping DP and HDMI connectors for the same port. > > 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 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > http://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Ville Syrjälä Intel OTC _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
