On Mon, Aug 24, 2020 at 06:48:37PM +0200, Jean-Christophe Barnoud wrote: > Hello. > > The team at libusb says that this is a kernel issue so here it is. > Device : Sound Devices MixPre-D > This is an external audio interface that worked simultaneously as input and > output with older kernels and libusb versions (see far below with fedora 26, > kernel 4.13.13-200, libusb 0.1.5-8 from an older mothballed machine). > With newer versions of the kernel and libusb it works only as output (see > just below with a current fedora 32, kernel 5.7.15-200, libusb-0.1.5-16). > > An online search shows that the dmesg output "duplicate endpoint" is > identical to the one referenced in this permalink : > http://archive.lwn.net:8080/linux-kernel/20200201105829.5682c887@acme7.acmenet/ > So I guess that the solution is the same, adding in > drivers/usb/core/quirks.c (adapted to the specific hardware identification) > : > + /* Sound Devices MixPre-D */ > + { USB_DEVICE(0x0926, 0x0208), .driver_info = > USB_QUIRK_ENDPOINT_BLACKLIST }, More than just this entry is needed; there also has to be an entry listing the endpoints to be ignored. But that's straightforward to add. > + > Would it be possible to add this exception to quirks.c ? > Thanks > > > Fedora 32 > > [jcb@localhost ~]$ dmesg > [181470.940975] usb 3-9: new high-speed USB device number 6 using xhci_hcd > [181471.067606] usb 3-9: config 1 interface 2 altsetting 1 has a duplicate > endpoint with address 0x85, skipping > [181471.067609] usb 3-9: config 1 interface 2 altsetting 2 has a duplicate > endpoint with address 0x85, skipping Can you provide the output from "lsusb -v" for this device? We'd like to know exactly what's being added to the ignore list and why, before doing it. Alan Stern
