Waldemar Brodkorb wrote: >> [ 547.352746] usb 3-5.2: 3:1: usb_set_interface failed (-28) >> [ 548.352865] usb 3-5.3: Not enough bandwidth for new device state. >> [ 548.352868] usb 3-5.3: Not enough bandwidth for altsetting 1 >> >> I have connected a 7-Port USB 3.0 Hub to my machine. >> I have 6 different Headsets and USB Soundcards connected to the HUB. >> >> As soon as I start a C++ application which opens all ALSA devices >> I get these errors and the USB stopps working correctly. >> >> I think the maximum count of USB sound devices, which behave stable >> is three or four. >> >> Is this some miscalculation of the Linux kernel regarding the USB >> bandwidth usage? How I can determine how much bandwidth the USB >> sound card driver preallocates? >> >> Or are five USB soundcards really too much for an USB 3.0 bus? > > There is no webcam involved, which usually uses MaxPacketsize of 1024, > so why I get the overallocation? AFAIK on xHCI controllers, the kernel and the controller's firmware must work together to handle this. It's possible that a USB 2.0 hub might work better. Try asking on the linux-usb list. Regards, Clemens _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
