| Message ID | 1417766884-8383-3-git-send-email-harinik@xilinx.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Dec 5, 2014 at 1:38 PM, Harini Katakam <harinik@xilinx.com> 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@xilinx.com> > Signed-off-by: Vishnu Motghare <vishnum@xilinx.com> > --- > > v3: > Add warning in case of unsupported transfer. > Reviewed-by: Rajeev Kumar <rajeevkumar.linux@gmail.com> > v2: > Dont defeteature repeated start. Just check for unsupported conditions in the > driver and return error. > > --- > drivers/i2c/busses/i2c-cadence.c | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c > index 5f5d4fa..3ea3b7a 100644 > --- a/drivers/i2c/busses/i2c-cadence.c > +++ b/drivers/i2c/busses/i2c-cadence.c > @@ -541,6 +541,21 @@ 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\t"); > + dev_warn(adap->dev.parent, > + "receive is followed by a transfer\n"); > + return -EOPNOTSUPP; > + } > id->bus_hold_flag = 1; > reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET); > reg |= CDNS_I2C_CR_HOLD; > -- > 1.7.9.5 > > -- > 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
Hi Harini, On Fri, 2014-12-05 at 01:38PM +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@xilinx.com> > Signed-off-by: Vishnu Motghare <vishnum@xilinx.com> > --- > > 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 | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c > index 5f5d4fa..3ea3b7a 100644 > --- a/drivers/i2c/busses/i2c-cadence.c > +++ b/drivers/i2c/busses/i2c-cadence.c > @@ -541,6 +541,21 @@ 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\t"); > + dev_warn(adap->dev.parent, > + "receive is followed by a transfer\n"); Please make this a single dev_warn without a line break in the string. That way you can grep for the message in the sources. Thanks, Sören
diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c index 5f5d4fa..3ea3b7a 100644 --- a/drivers/i2c/busses/i2c-cadence.c +++ b/drivers/i2c/busses/i2c-cadence.c @@ -541,6 +541,21 @@ 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\t"); + dev_warn(adap->dev.parent, + "receive is followed by a transfer\n"); + return -EOPNOTSUPP; + } id->bus_hold_flag = 1; reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET); reg |= CDNS_I2C_CR_HOLD;