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sh: lockless gpio_set_value()

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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>
This commit is contained in:
Magnus Damm 2008-12-25 18:17:26 +09:00 • committed by Paul Mundt
parent 0fc64cc0a2
commit 3292094e88
2 changed files with 82 additions and 26 deletions
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2
arch/sh/include/asm/gpio.h
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@ -59,7 +59,7 @@ struct pinmux_cfg_reg {
.enum_ids = (pinmux_enum_t [(r_width / f_width) * (1 << f_width)]) \
struct pinmux_data_reg {
unsigned long reg, reg_width;
unsigned long reg, reg_width, reg_shadow;
pinmux_enum_t *enum_ids;
};