On Thu, Nov 12, 2020 at 6:20 PM Ruslan Bilovol <ruslan.bilovol@xxxxxxxxx> wrote: > > On Wed, Nov 11, 2020 at 11:30 AM Peter Chen <peter.chen@xxxxxxx> wrote: > > > > On 20-11-08 02:18:28, Ruslan Bilovol wrote: > > > Current UAC2 gadget implements capture/sync paths > > > as two USB ISO ASYNC endpoints (IN and OUT). > > > > > > This violates USB spec which says that ISO ASYNC OUT endpoint > > > should have feedback companion endpoint. > > > See USB2.0 spec "5.12.4.1 Synchronization Type": asynchronous > > > sink provides explicit feedback (isochronous pipe). > > > Interesting that for ISO ASYNC *IN* endpoint respective > > > feedback isn't required since source provides implicit > > > feedforward (data stream). > > > > > > While it's not an issue if UAC2 Gadget is connected to > > > Linux host (Linux ignores missing feedback endpoint), > > > with other hosts like Windows or MacOS the UAC2 Gadget > > > isn't enumerated due to missing feedback endpoint. > > > > > > This patch series adds feedback endpoint support to > > > UAC2 function, new control to UAC2 mixer which can > > > be used by userspace tools (like alsaloop from alsa-utils) > > > for updating feedback frequency reported to the host. > > > This is useful for usecases when UAC2 Gadget's audio > > > samples are played to another codec or audio card > > > with its own internal freerunning clock so host can > > > be notified that more/less samples are required. > > > > > > The alsaloop tool requires some (relatively small) > > > modifications in order to start support driving > > > feedback frequency through UAC2 mixer control. > > > That change will be sent as a separate patch > > > to ALSA community. > > > > > > Also added ability to switch ISO ASYNC OUT endpoint into > > > adaptive endpoint which doesn't require feedback endpoint > > > (as per USB spec). > > > > > > Ruslan Bilovol (3): > > > usb: gadget: f_uac2/u_audio: add feedback endpoint support > > > usb: gadget: f_uac2: add adaptive sync support for capture > > > usb: gadget: u_audio: add real feedback implementation > > > > Hi Ruslan, > > > > I applied your patches, but WIN10 still can't recognize it well. > > The UAC1 is OK for WIN10 with the below same configuration. > > Any debug information you would like to know to check it? > > > > > > if [ "$FUNC" == "uac2" ]; then > > mkdir functions/$FUNC".0" > > echo 2 > functions/$FUNC".0"/p_ssize > > echo 48000 > functions/$FUNC".0"/p_srate > > echo 3 > functions/$FUNC".0"/p_chmask > > > > echo 2 > functions/$FUNC".0"/c_ssize > > echo 48000 > functions/$FUNC".0"/c_srate > > echo 3 > functions/$FUNC".0"/c_chmask > > #echo 4 > functions/$FUNC".0"/req_number > > ln -s functions/$FUNC".0" configs/c.1 > > echo high-speed > /sys/kernel/config/usb_gadget/g1/max_speed > > fi > > > > Hmm... I just tested below config and it works fine with my Win10. > The only thing I noticed is Windows doesn't enable UAC2 gadget > by default, but this can be done from Win10 sound settings > > --------------------------------->8-------------------------------------- > mkdir cfg > mount none cfg -t configfs > mkdir cfg/usb_gadget/g1 > cd cfg/usb_gadget/g1 > mkdir configs/c.1 > mkdir functions/uac2.0 > > # 44.1 kHz sample rate > echo 44100 > functions/uac2.0/c_srate > echo 44100 > functions/uac2.0/p_srate > > mkdir strings/0x409 > mkdir configs/c.1/strings/0x409 > echo 0x0101 > idProduct > echo 0x1d6b > idVendor > echo my-serial-num > strings/0x409/serialnumber > echo my-manufacturer > strings/0x409/manufacturer > echo "Test gadget" > strings/0x409/product > echo "Conf 1" > configs/c.1/strings/0x409/configuration > echo 120 > configs/c.1/MaxPower > ln -s functions/uac2.0 configs/c.1 > echo musb-hdrc.0 > UDC > --------------------------------->8-------------------------------------- > > Thanks, > Ruslan Hi Ruslan - With your configuration (above) Win10 was able to recognize and load the driver. What appears to prevent my configuration from loading is the fact that I selected 48K as my sample rate and my capture/playback channel mask includes more than two (2) channels. If I take your configuration and change the sample rate (c_srate/p_srate) to 48000 Windows will fail to load the driver. Likewise, setting the c_chmask/p_chmask to 7 (three channels) will also cause the driver to fail to load. You mentioned there is an option in Win10 Sound Settings to "enable" UAC2 by default. I cannot find that option and I wonder if this is what is preventing me from changing the sample rate or channel mask? Could Windows be treating my audio gadget as a UAC1 device rather than a fully multi-channel audio device (even though the usbaudio2.sys driver is loaded)? Have you tried other configurations to verify your Win10 box supports more than two channels and a 44.1K sample rate? I look forward to your feedback and any suggestions you might offer. Thanks, Glenn
