• Kohji Okuno's avatar
    ARM: imx6q: cpuidle: fix bug that CPU might not wake up at expected time · 91740fc8
    Kohji Okuno authored
    In the current cpuidle implementation for i.MX6q, the CPU that sets
    'WAIT_UNCLOCKED' and the CPU that returns to 'WAIT_CLOCKED' are always
    the same. While the CPU that sets 'WAIT_UNCLOCKED' is in IDLE state of
    "WAIT", if the other CPU wakes up and enters IDLE state of "WFI"
    istead of "WAIT", this CPU can not wake up at expired time.
     Because, in the case of "WFI", the CPU must be waked up by the local
    timer interrupt. But, while 'WAIT_UNCLOCKED' is set, the local timer
    is stopped, when all CPUs execute "wfi" instruction. As a result, the
    local timer interrupt is not fired.
     In this situation, this CPU will wake up by IRQ different from local
    timer. (e.g. broacast timer)
    
    So, this fix changes CPU to return to 'WAIT_CLOCKED'.
    Signed-off-by: default avatarKohji Okuno <okuno.kohji@jp.panasonic.com>
    Fixes: e5f9dec8 ("ARM: imx6q: support WAIT mode using cpuidle")
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarShawn Guo <shawnguo@kernel.org>
    91740fc8
cpuidle-imx6q.c 2 KB