| Message ID | 1394521655-3444-1-git-send-email-mike.looijmans@topic.nl |
|---|---|
| State | Superseded |
| Headers | show |
Hi Mike, On Tue, 2014-03-11 at 08:07AM +0100, Mike Looijmans wrote: > Pressing CTRL-C while communicating with an I2C device leads to erratic > behaviour. The cause is that the controller will interrupt the I2C transfer > in progress, and leave the client device in an undefined state. Many > drivers do not handle error return codes on I2C transfers. The calling driver > has no way of telling how much of the transfer has actually completed, so > it cannot reliably determine the device's state. > > The best solution here is to not handle signals in the I2C bus driver at all, > but always complete a transaction before returning control. > > See for a related patch and discussion on this topic: > http://lkml.org/lkml/2014/1/9/246 > > Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl> Acked-by: Soren Brinkmann <soren.brinkmann@xilinx.com> Thanks for the update. I'll take these changes and resubmit the driver to LKML as well. Sören -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c index 86713d6..c61c3c9 100644 --- a/drivers/i2c/busses/i2c-cadence.c +++ b/drivers/i2c/busses/i2c-cadence.c @@ -452,16 +452,12 @@ static int cdns_i2c_process_msg(struct cdns_i2c *id, struct i2c_msg *msg, cdns_i2c_msend(id); /* Wait for the signal of completion */ - ret = wait_for_completion_interruptible_timeout( - &id->xfer_done, HZ); - if (ret < 1) { + ret = wait_for_completion_timeout(&id->xfer_done, HZ); + if (!ret) { cdns_i2c_master_reset(adap); - if (!ret) { - dev_err(id->adap.dev.parent, + dev_err(id->adap.dev.parent, "timeout waiting on completion\n"); - return -ETIMEDOUT; - } - return ret; + return -ETIMEDOUT; } cdns_i2c_writereg(CDNS_I2C_IXR_ALL_INTR_MASK, CDNS_I2C_IDR_OFFSET);
Pressing CTRL-C while communicating with an I2C device leads to erratic behaviour. The cause is that the controller will interrupt the I2C transfer in progress, and leave the client device in an undefined state. Many drivers do not handle error return codes on I2C transfers. The calling driver has no way of telling how much of the transfer has actually completed, so it cannot reliably determine the device's state. The best solution here is to not handle signals in the I2C bus driver at all, but always complete a transaction before returning control. See for a related patch and discussion on this topic: http://lkml.org/lkml/2014/1/9/246 Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl> --- drivers/i2c/busses/i2c-cadence.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-)