Commit 3fd306c8 authored Nov 02, 2011 by Jan Weitzel Committed by Linus Torvalds Nov 02, 2011

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>

parent 68a436ae

drivers/w1/w1_io.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -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;

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