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w1: disable irqs in critical section 

Interrupting w1_delay() in w1_read_bit() results in missing the low level
on the w1 line and receiving "1" instead of "0".

Add local_irq_save()/local_irq_restore() around the critical section

Signed-off-by: Jan Weitzel <j.weitzel@phytec.de>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jan Weitzel 2011-11-02 13:40:02 -07:00 committed by Linus Torvalds
parent 68a436aec3
commit 3fd306c85a
1 changed files with 5 additions and 0 deletions
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5
drivers/w1/w1_io.c
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@ -158,13 +158,18 @@ EXPORT_SYMBOL_GPL(w1_write_8);
static u8 w1_read_bit(struct w1_master *dev)
{
int result;
unsigned long flags;
/* sample timing is critical here */
local_irq_save(flags);
dev->bus_master->write_bit(dev->bus_master->data, 0);
w1_delay(6);
dev->bus_master->write_bit(dev->bus_master->data, 1);
w1_delay(9);
result = dev->bus_master->read_bit(dev->bus_master->data);
local_irq_restore(flags);
w1_delay(55);
return result & 0x1;