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Commit 3fd306c8 authored by Jan Weitzel's avatar Jan Weitzel Committed by Linus Torvalds
Browse files

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: default avatarJan Weitzel <j.weitzel@phytec.de>
Acked-by: default avatarEvgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus 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;