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.
Signed-off-by: Marc Kleine-Budde <[email protected]>
Reviewed-by: Wolfram Sang <[email protected]>
---
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
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 <[email protected]>
> Reviewed-by: Wolfram Sang <[email protected]>
> ---
>
> 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 ([email protected], http://www.fluff.org/)
'a smiley only costs 4 bytes'
Ben Dooks wrote:
> 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?
The caller of the caller does this. "i2c_imx_xfer" will call
"i2c_imx_stop", and this function will generate the stop condition if
not already done so.
I'm sending a V3 version of the patch, which removes the only written to
variable "result".
cheers, Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
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