parent a49f0d1ea3ec94fc7cf33a7c36a16343b74bd565 author Sarah Sharp 1355782355 -0800 committer Sarah Sharp 1357250995 -0800 xhci: Handle HS bulk/ctrl endpoints that don't NAK. A high speed control or bulk endpoint may have bInterval set to zero, which means it does not NAK. If bInterval is non-zero, it means the endpoint NAKs at a rate of 2^(bInterval - 1). The xHCI code to compute the NAK interval does not handle the special case of zero properly. The current code unconditionally subtracts one from bInterval and uses it as an exponent. This causes a very large bInterval to be used, and warning messages like these will be printed: usb 1-1: ep 0x1 - rounding interval to 32768 microframes, ep desc says 0 microframes This may cause the xHCI host hardware to reject the Configure Endpoint command, which means the HS device will be unusable under xHCI ports. This patch should be backported to kernels as old as 2.6.31, that contain commit dfa49c4ad120a784ef1ff0717168aa79f55a483a "USB: xhci - fix math in xhci_get_endpoint_interval()". Reported-by: Vincent Pelletier Suggested-by: Alan Stern Signed-off-by: Sarah Sharp Cc: stable@vger.kernel.org ˝