Prev: WARNING!
Next: [Bug #16201] SIOCGIWFREQ ioctl fails to get frequency info
From: Ben Dooks on 20 Jun 2010 18:40
On Tue, Jun 15, 2010 at 12:20:38PM +0200, Marc Kleine-Budde wrote:
> The i2c_imx_trx_complete() 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 receives a signal, the wait will be
> interrupted, returning an error. It is better to let the I2C operation
> finished before handling the signal (i.e. returning into userspace).
>
> 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.

Hmm, if it times out, do you need to at-least try sending a stop
on the bus? or does the caller do that for you?

> Signed-off-by: Marc Kleine-Budde <mkl(a)pengutronix.de>
> Reviewed-by: Wolfram Sang <w.sang(a)pengutronix.de>
> ---
>
> V2: Remove check for "result < 0" as commented by Wolfram Sang.
>
> drivers/i2c/busses/i2c-imx.c | 9 +++------
> 1 files changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index d1ff940..58df809 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -161,13 +161,10 @@ static int i2c_imx_trx_complete(struct
> imx_i2c_struct *i2c_imx)
> {
> int result;
>
> - result = wait_event_interruptible_timeout(i2c_imx->queue,
> + result = wait_event_timeout(i2c_imx->queue,
> i2c_imx->i2csr & I2SR_IIF, HZ / 10);
>
> - if (unlikely(result < 0)) {
> - dev_dbg(&i2c_imx->adapter.dev, "<%s> result < 0\n", __func__);
> - return result;
> - } else if (unlikely(!(i2c_imx->i2csr & I2SR_IIF))) {
> + if (unlikely(!(i2c_imx->i2csr & I2SR_IIF))) {
> dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", __func__);
> return -ETIMEDOUT;
> }
> @@ -295,7 +292,7 @@ static irqreturn_t i2c_imx_isr(int irq, void *dev_id)
> i2c_imx->i2csr = temp;
> temp &= ~I2SR_IIF;
> writeb(temp, i2c_imx->base + IMX_I2C_I2SR);
> - wake_up_interruptible(&i2c_imx->queue);
> + wake_up(&i2c_imx->queue);
> return IRQ_HANDLED;
> }
>
> --
> 1.7.1
>



--
Ben (ben(a)fluff.org, http://www.fluff.org/)

'a smiley only costs 4 bytes'
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
 | 
Pages: 1
Prev: WARNING!
Next: [Bug #16201] SIOCGIWFREQ ioctl fails to get frequency info