From: Magnus Damm <damm@igel.co.jp>
Date: Thu, 25 Dec 2008 09:17:26 +0000 (+0900)
Subject: sh: lockless gpio_set_value()
X-Git-Tag: v2.6.30-rc1~673^2~97
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3292094e88ce6b76714dad8ec4b43d7c5c12ada2;p=pandora-kernel.git

sh: lockless gpio_set_value()

This patch optimizes the gpio data register handling for gpio_set_value().

Instead of using the good old spinlock-plus-read-modify-write strategy
we now use a shadow register and atomic operations.

This improves the bitbanging mmc performance on Migo-R from 26 Kbytes/s
to 40 Kbytes/s.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
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