On Fri, Feb 06, 2009 at 08:00:37AM -0600, Timur Tabi wrote:
> The i2c_wait() function is using wait_event_interruptible_timeout() to wait for
> the I2C controller to signal that it has completed an I2C bus operation. If
> the process that causes the I2C operation terminated abruptly, the wait will
> be interrupted, returning an error. It is better to let the I2C operation
> finished before the process exits.
>
> It is safe to use wait_event_timeout() instead, because the timeout will allow
> the process to exit if the I2C bus hangs. It's also better to allow the
> I2C operation to finish, because unacknowledged I2C operations can cause the
> I2C bus to hang.
>
> Signed-off-by: Timur Tabi <timur@xxxxxxxxxxxxx>
Acked-by: Ben Dooks <ben-linux@xxxxxxxxx>
> ---
>
> A similar change should probably be done to i2c-cpm.c, and maybe all other
> I2C drivers. Not many use wait_event_interruptible_timeout().
>
> drivers/i2c/busses/i2c-mpc.c | 9 +++------
> 1 files changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
> index a9a45fc..c0ace48 100644
> --- a/drivers/i2c/busses/i2c-mpc.c
> +++ b/drivers/i2c/busses/i2c-mpc.c
> @@ -70,7 +70,7 @@ static irqreturn_t mpc_i2c_isr(int irq, void *dev_id)
> /* Read again to allow register to stabilise */
> i2c->interrupt = readb(i2c->base + MPC_I2C_SR);
> writeb(0, i2c->base + MPC_I2C_SR);
> - wake_up_interruptible(&i2c->queue);
> + wake_up(&i2c->queue);
> }
> return IRQ_HANDLED;
> }
> @@ -115,13 +115,10 @@ static int i2c_wait(struct mpc_i2c *i2c, unsigned timeout, int writing)
> writeb(0, i2c->base + MPC_I2C_SR);
> } else {
> /* Interrupt mode */
> - result = wait_event_interruptible_timeout(i2c->queue,
> + result = wait_event_timeout(i2c->queue,
> (i2c->interrupt & CSR_MIF), timeout * HZ);
>
> - if (unlikely(result < 0)) {
> - pr_debug("I2C: wait interrupted\n");
> - writeccr(i2c, 0);
> - } else if (unlikely(!(i2c->interrupt & CSR_MIF))) {
> + if (unlikely(!(i2c->interrupt & CSR_MIF))) {
> pr_debug("I2C: wait timeout\n");
> writeccr(i2c, 0);
> result = -ETIMEDOUT;
> --
> 1.5.5
>
> --
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--
Ben (ben@xxxxxxxxx, http://www.fluff.org/)
'a smiley only costs 4 bytes'
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