nak: Loop to ensure we get accurate shader clocks
Even though CS2R can fetch a whole 64 bits at a time, that doesn't mean it does so atomically. Instead, we need to loop, alternating high and low until we fetch the same high value twice.
Even though CS2R can fetch a whole 64 bits at a time, that doesn't mean it does so atomically. Instead, we need to loop, alternating high and low until we fetch the same high value twice.