display works sortof

[rpikern] / doc / notes.md

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 Raspberry Pi2 notes
 ===================
-The following is not all confirmed.
+Accessing different peripherals migh return results out of order. See bcm2835
+spec section 1.3. Use memory barriers as follows:
+ - place write barrier before the first write to a peripheral
+ - place read barrier after the last read of a peripheral
+
+Multiple accesses to the same peripheral in a row do not require barriers.
+
+Interrupt handlers should have a read barrier before their first read, and end
+with a write barrier.
+
+Cache clean and invalidate operations are also needed before the GPU can see our
+command buffers... see:
+https://github.com/rsta2/uspi/blob/38eaff4f715643a9/lib/synchronize.c
 
 Memory map
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