w1_io.c 1.7
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 <[email protected]>
---
drivers/w1/w1_io.c | 14 +++++++++++++-
1 files changed, 13 insertions(+), 1 deletions(-)
diff --git a/drivers/w1/w1_io.c b/drivers/w1/w1_io.c
index 46c6994..9238758 100644
--- a/drivers/w1/w1_io.c
+++ b/drivers/w1/w1_io.c
@@ -291,12 +291,24 @@ int w1_reset_bus(struct w1_master *dev)
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;
--
1.4.4.4
On Fri, Mar 28, 2008 at 07:26:55AM -0500, David Fries ([email protected]) wrote:
> w1_io.c 1.7
> 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.
Ack.
--
Evgeniy Polyakov