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    xhci: Properly handle COMP_2ND_BW_ERR · 71d85724
    Hans de Goede 提交于
    I encountered a result of COMP_2ND_BW_ERR while improving how the pwc
    webcam driver handles not having the full usb1 bandwidth available to
    itself.
    
    I created the following test setup, a NEC xhci controller with a
    single TT USB 2 hub plugged into it, with a usb keyboard and a pwc webcam
    plugged into the usb2 hub. This caused the following to show up in dmesg
    when trying to stream from the pwc camera at its highest alt setting:
    
    xhci_hcd 0000:01:00.0: ERROR: unexpected command completion code 0x23.
    usb 6-2.1: Not enough bandwidth for altsetting 9
    
    And usb_set_interface returned -EINVAL, which caused my pwc code to not
    do the right thing as it expected -ENOSPC.
    
    This patch makes the xhci driver properly handle COMP_2ND_BW_ERR and makes
    usb_set_interface return -ENOSPC as expected.
    
    This should be backported to stable kernels as old as 2.6.32.
    Signed-off-by: NHans de Goede <hdegoede@redhat.com>
    Signed-off-by: NSarah Sharp <sarah.a.sharp@linux.intel.com>
    Cc: stable@vger.kernel.org
    71d85724
xhci.h 60.7 KB