From: Mike Frysinger Date: Mon, 27 Jun 2011 03:11:19 +0000 (-0400) Subject: Blackfin: dpmc: optimize hibernate/resume path X-Git-Tag: v3.1-rc1~268^2~10 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=eed7b8365807549c67613ea7d9a451262050ba3e;p=pandora-kernel.git Blackfin: dpmc: optimize hibernate/resume path The current save logic used in hibernation is to do a MMR load (base + offset) into a register, and then push that onto the stack. Then when restoring, pop off the stack into a register followed by a MMR store (base + offset). These use plenty of 32bit insns rather than 16bit, are pretty long winded, and full of pipeline bubbles. So, by taking advantage of MMRs that are contiguous, the multi-register push/pop insn, and register abuse, we can shrink this code considerably. When saving, the new logic does a lot of loads into the data and pointer registers before executing a single multi-register push insn. Then when restoring, we do a single multi-register pop insn followed by a lot of stores. Overall, this allows us to cut the insn count by ~30%, the code size by ~45%, and drastically reduce the register hazards that trigger bubbles in the pipeline. Signed-off-by: Mike Frysinger --- Reading git-diff-tree failed