From 6e10f65427ed800ad1026dbf8064ca536ea98afc Mon Sep 17 00:00:00 2001 From: David Fries Date: Wed, 15 Oct 2008 22:05:05 -0700 Subject: W1: ds2490.c simplify and fix ds_touch_bit Simplify and fix ds_touch_bit. If a device is attached in the middle of a bus search the status register will return more than the default 16 bytes. The additional bytes indicate that it has detected a new device. The way ds_wait_status is coded, if it doesn't read 16 status bytes it returns an error value. ds_touch_bit then will detect that error and return an error. In that case it doesn't read the input buffer and returns uninitialized data. It doesn't stop there. The next transaction will not expect the extra byte in the input buffer and the short read will cause an error and clear out both the old byte and new data in the input buffer. Just ignore the value of ds_wait_status. It is still required to wait until ds2490 is again idle and there is data to read when ds_recv_data is called. This also removes the while loop. None of the other commands wait and verify that the issued command is in the status register. Signed-off-by: David Fries Signed-off-by: Evgeniy Polyakov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/w1/masters/ds2490.c | 21 ++++----------------- 1 file changed, 4 insertions(+), 17 deletions(-) (limited to 'drivers') diff --git a/drivers/w1/masters/ds2490.c b/drivers/w1/masters/ds2490.c index 1b632d549e7..c4ff70b2c7c 100644 --- a/drivers/w1/masters/ds2490.c +++ b/drivers/w1/masters/ds2490.c @@ -490,28 +490,15 @@ static int ds_set_pullup(struct ds_device *dev, int delay) static int ds_touch_bit(struct ds_device *dev, u8 bit, u8 *tbit) { - int err, count; + int err; struct ds_status st; - u16 value = (COMM_BIT_IO | COMM_IM) | ((bit) ? COMM_D : 0); - u16 cmd; - err = ds_send_control(dev, value, 0); + err = ds_send_control(dev, COMM_BIT_IO | COMM_IM | (bit ? COMM_D : 0), + 0); if (err) return err; - count = 0; - do { - err = ds_wait_status(dev, &st); - if (err) - return err; - - cmd = st.command0 | (st.command1 << 8); - } while (cmd != value && ++count < 10); - - if (err < 0 || count >= 10) { - printk(KERN_ERR "Failed to obtain status.\n"); - return -EINVAL; - } + ds_wait_status(dev, &st); err = ds_recv_data(dev, tbit, sizeof(*tbit)); if (err < 0) -- cgit v1.2.3