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>
diff --git a/drivers/w1/w1_io.c b/drivers/w1/w1_io.c
index 765b37b..3135b2c 100644
--- a/drivers/w1/w1_io.c
+++ b/drivers/w1/w1_io.c
@@ -158,13 +158,18 @@
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;
