On Thu, 2014-12-11 at 12:46PM +0530, Harini Katakam wrote:
> Hi Soren,
>
> On Wed, Dec 10, 2014 at 11:15 PM, Sören Brinkmann
> <soren.brinkmann@xxxxxxxxxx> wrote:
> > On Wed, 2014-12-10 at 05:14PM +0530, Harini Katakam wrote:
> >> Cadence I2C controller has the following bugs:
> >> - completion indication is not given to the driver at the end of
> >> a read/receive transfer with HOLD bit set.
> >> - Invalid read transaction are generated on the bus when HW timeout
> >> condition occurs with HOLD bit set.
> >>
> >> As a result of the above, if a set of messages to be transferred with
> >> repeated start includes any transfer following a read transfer,
> >> completion is never indicated and timeout occurs.
> >> Hence a check is implemented to return -EOPNOTSUPP for such sequences.
> >>
> >> Signed-off-by: Harini Katakam <harinik@xxxxxxxxxx>
> >> Signed-off-by: Vishnu Motghare <vishnum@xxxxxxxxxx>
> >> ---
> >>
> >> v4:
> >> Use single dev_warn and make message grep-able.
> >>
> >> v3:
> >> Add warning in case of unsupported transfer.
> >>
> >> v2:
> >> Dont defeteature repeated start. Just check for unsupported conditions in the
> >> driver and return error.
> >>
> >> ---
> >> drivers/i2c/busses/i2c-cadence.c | 14 ++++++++++++++
> >> 1 file changed, 14 insertions(+)
> >>
> >> diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c
> >> index 5f5d4fa..f9269a6 100644
> >> --- a/drivers/i2c/busses/i2c-cadence.c
> >> +++ b/drivers/i2c/busses/i2c-cadence.c
> >> @@ -541,6 +541,20 @@ static int cdns_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
> >> * processed with a repeated start.
> >> */
> >> if (num > 1) {
> >> + /*
> >> + * This controller does not give completion interrupt after a
> >> + * master receive transfer if HOLD bit is set (repeated start),
> >> + * resulting in SW timeout. Hence, if a receive transfer is
> >> + * followed by any other transfer, an error is returned
> >> + * indicating that this sequence is not supported.
> >> + */
> >> + for (count = 0; count < num-1; count++) {
> >> + if (msgs[count].flags & I2C_M_RD)
> >> + dev_warn(adap->dev.parent, "No support for "
> >> + "repeated start when receive is "
> >> + "followed by a transfer\n");
> >
> > Still not grepable. There must be no line breaks in the string!
>
> This message will be printed in one single line.
> Do you want this string to be grepable in the driver? Why is that necessary?
It's about grepping the sources.
I pointed you to the paragraph in the Codingstyle rules, please read
it.
Sören
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