Commits
Sarah Sharp committed f217c980ca9
xhci: Don't enable/disable RWE on bus suspend/resume. The RWE bit of the USB 2.0 PORTPMSC register is supposed to enable remote wakeup for devices in the lower power link state L1. It has nothing to do with the device suspend remote wakeup from L2. The RWE bit is designed to be set once (when USB 2.0 LPM is enabled for the port) and cleared only when USB 2.0 LPM is disabled for the port. The xHCI bus suspend method was setting the RWE bit erroneously, and the bus resume method was clearing it. The xHCI 1.0 specification with errata up to Aug 12, 2012 says in section 4.23.5.1.1.1 "Hardware Controlled LPM": "While Hardware USB2 LPM is enabled, software shall not modify the HIRDBESL or RWE fields of the USB2 PORTPMSC register..." If we have previously enabled USB 2.0 LPM for a device, that means when the USB 2.0 bus is resumed, we violate the xHCI specification by clearing RWE. It also means that after a bus resume, the host would think remote wakeup is disabled from L1 for ports with USB 2.0 Link PM enabled, which is not what we want. This patch should be backported to kernels as old as 3.2, that contain the commit 65580b4321eb36f16ae8b5987bfa1bb948fc5112 "xHCI: set USB2 hardware LPM". That was the first kernel that supported USB 2.0 Link PM. Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Cc: stable@vger.kernel.org