W1: w1_io.c reset comments and msleep
w1_reset_bus, added some comments about the timing and switched to msleep
for the later delay. I don't have the hardware to test the sleep after
reset change. The one wire doesn't have a timing requirement between
commands so it is fine. I do have the USB hardware and it would be in big
trouble with 10ms interrupt transfers to find that the reset completed.
Signed-off-by: David Fries <david@fries.net>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
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 97b338a..f4f82f1 100644
--- a/drivers/w1/w1_io.c
+++ b/drivers/w1/w1_io.c
@@ -293,12 +293,24 @@
result = dev->bus_master->reset_bus(dev->bus_master->data) & 0x1;
else {
dev->bus_master->write_bit(dev->bus_master->data, 0);
+ /* minimum 480, max ? us
+ * be nice and sleep, except 18b20 spec lists 960us maximum,
+ * so until we can sleep with microsecond accuracy, spin.
+ * Feel free to come up with some other way to give up the
+ * cpu for such a short amount of time AND get it back in
+ * the maximum amount of time.
+ */
w1_delay(480);
dev->bus_master->write_bit(dev->bus_master->data, 1);
w1_delay(70);
result = dev->bus_master->read_bit(dev->bus_master->data) & 0x1;
- w1_delay(410);
+ /* minmum 70 (above) + 410 = 480 us
+ * There aren't any timing requirements between a reset and
+ * the following transactions. Sleeping is safe here.
+ */
+ /* w1_delay(410); min required time */
+ msleep(1);
}
return result;
