Hi Luca, On 3/21/2025 6:13 AM, Luca Weiss wrote: > Hi Wesley, > > On Wed Mar 19, 2025 at 1:51 AM CET, Wesley Cheng wrote: >> Requesting to see if we can get some Acked-By tags, and merge on usb-next. >> >> Several Qualcomm based chipsets can support USB audio offloading to a >> dedicated audio DSP, which can take over issuing transfers to the USB >> host controller. The intention is to reduce the load on the main >> processors in the SoC, and allow them to be placed into lower power modes. >> There are several parts to this design: >> 1. Adding ASoC binding layer >> 2. Create a USB backend for Q6DSP >> 3. Introduce XHCI interrupter support >> 4. Create vendor ops for the USB SND driver >> > > I was able to test this series (v35) on SM6350/SM7225 Fairphone 4 > smartphone and it appears to work as expected! Thank you for taking the time to testing this :), much appreciated. > > Based on the sm8350 branch you shared[0] I added similar dts bits for my > device, I've pushed that branch here[1] for reference. > > [0] https://git.codelinaro.org/clo/linux-kernel/kernel-qcom/-/commits/usb_audio_offload/ > [1] https://github.com/sm6350-mainline/linux/commits/sm6350-6.14-wip-usb-snd-offload/ > > And I've used these commands to test: > > fairphone-4:~$ amixer -c0 cset name='USB Mixer MultiMedia2' On > > fairphone-4:~$ aplay -l > **** List of PLAYBACK Hardware Devices **** > card 0: F4 [Fairphone 4], device 0: MultiMedia1 (*) [] > Subdevices: 1/1 > Subdevice #0: subdevice #0 > card 0: F4 [Fairphone 4], device 1: MultiMedia2 (*) [] > Subdevices: 1/1 > Subdevice #0: subdevice #0 > card 1: Audio [Hi-Res Audio], device 0: USB Audio [USB Audio] > Subdevices: 1/1 > Subdevice #0: subdevice #0 > > fairphone-4:~$ ffmpeg -i test.m4a -acodec pcm_s16le test.wav > > fairphone-4:~$ aplay --device=plughw:0,1 Music/test.wav > Playing WAVE 'Music/test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo > > And then music was coming out of these headphones connected via a USB-C > to 3.5mm dongle. > > Every time I'm starting playback this error appears in dmesg, do you > also see this on your test setup? > > [ 1336.081525] q6afe-dai 3000000.remoteproc:glink-edge:apr:service@4:dais: AFE Port already open > The print is coming because the Q6 USB backend DAI link is utilizing the q6afe_port_get_from_id() API to fetch the proper AFE port to issue commands to. IMO, that log level should be decreased to at least dev_info() instead of an error, but we can probably take that discussion into a different series. To add, I also see this on my set up. > > And if I'm not mistaken it's possible to check that actually the offload > path is getting used by checking the interrupt counts of the xhci-hcd > interrupt. > > With regular USB audio card playback there's many interrupts per second > happening: > > fairphone-4:~$ aplay --device=plughw:1,0 Music/test.wav # regular USB > fairphone-4:~$ cat /proc/interrupts | grep -i usb > 188: 137524 0 0 0 0 0 0 0 GICv3 165 Level xhci-hcd:usb1 > fairphone-4:~$ cat /proc/interrupts | grep -i usb > 188: 137591 0 0 0 0 0 0 0 GICv3 165 Level xhci-hcd:usb1 > > And with the offload card during playback there's no interrupts > happening (just a few when initially starting playback): > > fairphone-4:~$ aplay --device=plughw:0,1 Music/test.wav # offload > fairphone-4:~$ cat /proc/interrupts | grep -i usb > 188: 141947 0 0 0 0 0 0 0 GICv3 165 Level xhci-hcd:usb1 > fairphone-4:~$ cat /proc/interrupts | grep -i usb > 188: 141947 0 0 0 0 0 0 0 GICv3 165 Level xhci-hcd:usb1 > This is correct. With offload enabled, you should probably only see a few interrupts from xHCI from the initial USB headset enumeration and control transfers, but the data packets itself should result in no increase of the xHCI IRQ. Thanks Wesley Cheng
