sync_begin - cache invalidate, should be called before cpu read
sync_end - cache flush, should be called after cpu write
MppBuffer sync flow:
1. hw access
2. sync_begin
3. cpu access (read / write)
4. sync_end
5. hw access
NOTE: readonly option is faster for read only buffer.
Signed-off-by: xueman.ruan <xueman.ruan@rock-chips.com>
Signed-off-by: Herman Chen <herman.chen@rock-chips.com>
Change-Id: I253a6139e9bb30808c07075d64f17b5cfad8519a
