[RFC] w1: Disable irqs in critical section

From: Jan Weitzel
Date: Wed Sep 07 2011 - 13:43:28 EST


Interrupting w1_delay in w1_read_bit results in missing the low level
on the w1 line and receiving "1" instead of "0".
Adding local_irq_save / local_irq_restore around the critical section

Signed-off-by: Jan Weitzel <j.weitzel@xxxxxxxxx>
---
drivers/w1/w1_io.c | 5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/drivers/w1/w1_io.c b/drivers/w1/w1_io.c
index 8e8b64c..a059eaa 100644
--- a/drivers/w1/w1_io.c
+++ b/drivers/w1/w1_io.c
@@ -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;
--
1.7.0.4

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