xhci: Don't write zeroed pointers to xHC registers.
When xhci_mem_cleanup() is called, we can't be sure if the xHC is actually halted. We can ask the xHC to halt by writing to the RUN bit in the command register, but that might timeout due to a HW hang. If the host controller is still running, we should not write zeroed values to the event ring dequeue pointers or base tables, the DCBAA pointers, or the command ring pointers. Eric Fu reports his VIA VL800 host accesses the event ring pointers after a failed register restore on resume from suspend. The hypothesis is that the host never actually halted before the register write to change the event ring pointer to zero. Remove all writes of zeroed values to pointer registers in xhci_mem_cleanup(). Instead, make all callers of the function reset the host controller first, which will reset those registers to zero. xhci_mem_init() is the only caller that doesn't first halt and reset the host controller before calling xhci_mem_cleanup(). This should be backported to kernels as old as 2.6.32. Signed-off-by: NSarah Sharp <sarah.a.sharp@linux.intel.com> Tested-by: NElric Fu <elricfu1@gmail.com> Cc: stable@vger.kernel.org
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