3 Replies Latest reply on Mar 22, 2018 7:15 AM by Carlos_A

    maximum android phones supported to connect to the usb port on skylake platform

    fosulincong Community Member

      Hi everyone,recently i got some issues about the skylake platform usb connection,as we know ,EHCI is reduced on skylake platform,so we got only XHCI controller to handle all the usb connection,and i have checked the XHCI spec datasheet,it seems like the XHCI controller can handle the maximum 255 usb devices but the single usb device can occupy up to 31 endpoints.


      hardware platform:dell optiplex 7050


      usb controller: XHCI


      in our environment,we need to connect the maximum number of the android phone to test,in the old platform ( dell optiplex 9020),we can connect about 30 phones without any problem,but when it turns to 7050,we can only connect to about 20 phones ,i have used the ms usbview software  to check my usb controller status and usb connection,now I got the following problems that need you experts to explain

      1、when I press the usb controller (extensible host controller) in the usbview,it says number of ports :26 ,so it means i can only connect maximum 26 usb devices ? i have tried to connect the three ten-ports usb hub,the first two hubs is totally recognized as a ten-ports hub without problem,and the third hub is recognized as a 6-ports hub,so it means even if we use the usb hubs we cannot exceed the maximum port limitation?how is the number 26 calculated?

      2、i have connected about 20 andriod phones to the PC,and the rest android phones cannot be totally recognized and stucked in the devicefailedenumeration status,how to maximize the usb to android phone connection?I have checked that per  android phone occupy 4 endpoints

      3、if I installed a usb expandable card in the pcie slot, will the capacity be more that allow me to successfully connect more usb devices or it just increase the physical usb port quantity?

      4、if there is not the function to disable XHCI in the bios setup,any ideas to disable the xhci function inside the windows os ?