• Sasha Levin's avatar
    kvm tools: Fix serial port probing · 610a82c4
    Sasha Levin authored
    
    
    The process of probing the 8250 serial port is as follows:
    
    1. Start detecting IRQs
    
    2. Enable the IER register [At this point, the port is supposed to light
       the INTR].
    
    3. Stop detecting IRQs [At this point, the driver detects which IRQ
       belongs to that port].
    
    4. Disable IER register.
    
    Since we weren't enabling and disabling the IRQ based on IER writes, we
    would often fail the probing since the driver couldn't detect which IRQ
    is used by the port, and would just default that to 0.
    
    This would cause slowness and may have caused hangs. For me there is a
    significant increase in speed of the terminal after this patch.
    
    Signed-off-by: default avatarSasha Levin <levinsasha928@gmail.com>
    [ penberg@kernel.org: whitspace cleanup ]
    Signed-off-by: default avatarPekka Enberg <penberg@kernel.org>
    610a82c4