3.2.75-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Rajmohan Mani <rajmohan.mani@xxxxxxxxx> commit a5964396190d0c40dd549c23848c282fffa5d1f2 upstream. Existing Intel xHCI controllers require a delay of 1 mS, after setting the CMD_RESET bit in command register, before accessing any HC registers. This allows the HC to complete the reset operation and be ready for HC register access. Without this delay, the subsequent HC register access, may result in a system hang, very rarely. Verified CherryView / Braswell platforms go through over 5000 warm reboot cycles (which was not possible without this patch), without any xHCI reset hang. Signed-off-by: Rajmohan Mani <rajmohan.mani@xxxxxxxxx> Tested-by: Joe Lawrence <joe.lawrence@xxxxxxxxxxx> Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- drivers/usb/host/xhci.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -170,6 +170,16 @@ int xhci_reset(struct xhci_hcd *xhci) command |= CMD_RESET; xhci_writel(xhci, command, &xhci->op_regs->command); + /* Existing Intel xHCI controllers require a delay of 1 mS, + * after setting the CMD_RESET bit, and before accessing any + * HC registers. This allows the HC to complete the + * reset operation and be ready for HC register access. + * Without this delay, the subsequent HC register access, + * may result in a system hang very rarely. + */ + if (xhci->quirks & XHCI_INTEL_HOST) + udelay(1000); + ret = handshake(xhci, &xhci->op_regs->command, CMD_RESET, 0, 10 * 1000 * 1000); if (ret) -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html