Hi Mike/Soren,
> -----Original Message-----
> From: Sören Brinkmann [mailto:soren.brinkm...@xilinx.com]
> Sent: Tuesday, March 11, 2014 03:30
> To: Mike Looijmans; Michal Simek
> Cc: git; w...@the-dreams.de; linux-...@vger.kernel.org; linux-
> ker...@vger.kernel.org
> Subject: Re: [PATCH] i2c-cadence: Do not let signals interrupt I2C transfers
>
> Hi Mike,
>
> The cadence driver is not in mainline yet. I think for our vendor tree we can
> pretty much take it this way.
> Regarding getting this into mainline, I'll send another iteration of the
> change
> set and include these changes.
>
> On Mon, 2014-03-10 at 12:12PM +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
>
> Can we get your Signed-off-by, please?
>
> > ---
> > drivers/i2c/busses/i2c-cadence.c | 12 ++++--------
> > 1 file changed, 4 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-cadence.c
> > b/drivers/i2c/busses/i2c-cadence.c
> > index 86713d6..32ce2ee 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 == 0) {
>
> To match the style used throughout the file this should just be
> if (!ret) {
Instead of discarding Ctrl+C, Can we wait until the current msg transfer
completes
[to avoid client undefined state or re-init the host to a known state]
I see da-vinci driver handling in a similar way.
Regards,
Suneel
>
>
> Acked-by: Soren Brinkmann <soren.brinkm...@xilinx.com>
>
> Thanks,
> Sören
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