On Wed, Mar 04, 2015 at 05:59:50PM +0000, Andre Przywara wrote:

The PL011 register UART_MIS is actually a bitwise AND of the
UART_RIS and the UART_MISC register.
Since the SBSA UART does not include the _MIS register, use the
two separate registers to get the same behaviour. Since we are
inside the spinlock and we read the _IMSC register only once, there
should be no race issue.

Do we really need to go all the way to the hardware for this?  Isn't
uap->im sufficient?  Reading from memory is potentially faster as it
could be in the CPU caches.

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