Subject: Re: Re: [PATCH] i2c: cadence: try reset when master receive error interrupts

From: "[email-masked]" <[email-masked]>
Date: Mon, 18 Feb 2019 15:16:37 +0800

Hi , Shubhrajyoti

>Hi ,
>On Sat, Feb 16, 2019 at 1:21 PM [email-masked] <[email-masked]> wrote:
>>
>> >Hi Sxauwsk,
>> >
>> >On Wed, Jan 30, 2019 at 3:13 PM sxauwsk <[email-masked]> wrote:
>> >>
>> >> When the adapter receive error interrupts, such as NACK, arbitration lost,
>> >> cdns_i2c_master_xfer return to the caller directly instead of resuming
>> >> the adapter which resulted in the adapter being out of control.
>> >>
>> >> So when driver detect err_status then try to repair and fix it.
>> >>
>> >> Signed-off-by: sxauwsk <[email-masked]>
>> >> ---
>> >>  drivers/i2c/busses/i2c-cadence.c | 12 +++++++-----
>> >>  1 file changed, 7 insertions(+), 5 deletions(-)
>> >>
>> >> diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c
>> >> index b13605718291..e10048d7524a 100644
>> >> --- a/drivers/i2c/busses/i2c-cadence.c
>> >> +++ b/drivers/i2c/busses/i2c-cadence.c
>> >> @@ -548,10 +548,6 @@ static int cdns_i2c_process_msg(struct cdns_i2c *id, struct i2c_msg *msg,
>> >>         cdns_i2c_writereg(CDNS_I2C_IXR_ALL_INTR_MASK,
>> >>                           CDNS_I2C_IDR_OFFSET);
>> >>
>> >> -       /* If it is bus arbitration error, try again */
>> >> -       if (id->err_status & CDNS_I2C_IXR_ARB_LOST)
>> >> -               return -EAGAIN;
>> >> -
>> >>         return 0;
>> >>  }
>> >>
>> >> @@ -617,13 +613,19 @@ static int cdns_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
>> >>                         id->bus_hold_flag = 0;
>> >>
>> >>                 ret = cdns_i2c_process_msg(id, msgs, adap);
>> >> -               if (ret)
>> >> +               if (!ret)
>> >>                         goto out;
>> >>
>> >In case  the Arbitration error happend  the cdns_i2c_process_msg would return 0
>> >and we will miss the check  below.
>> >
>> >Am I missing something ?
>> >
>> >>                 /* Report the other error interrupts to application */
>> >>                 if (id->err_status) {
>> >>                         cdns_i2c_master_reset(adap);
>> >>
>> >> +                       /* If it is bus arbitration error, try again */
>> >> +                       if (id->err_status & CDNS_I2C_IXR_ARB_LOST) {
>> >> +                               ret = -EAGAIN;
>> >> +                               goto out;
>> >> +                       }
>> >> +
>> >>                         if (id->err_status & CDNS_I2C_IXR_NACK) {
>> >>                                 ret = -ENXIO;
>> >>                                 goto out;
>> >> --
>> >> 2.19.2
>> >>
>> >>
>>
>> In cdns_i2c_process_msg process, when detect arbitration lost error return -EAGAIN to  cdns_i2c_master_xfer,  not return 0
>> that mean cdns_i2c_process_msg  just go out ignore error check and  problem occur, So we should do something when arbitration error detect.
>
>Arbitration lost is fine how about other errors like NACK. 

>> >>                 ret = cdns_i2c_process_msg(id, msgs, adap);
>> >> -               if (ret)
>> >> +               if (!ret)
>> >>                         goto out;

Yes, you're right,  This place I should't make any change,  perfect solution!

>> >>
>> >> -       /* If it is bus arbitration error, try again */
>> >> -       if (id->err_status & CDNS_I2C_IXR_ARB_LOST)
>> >> -               return -EAGAIN;
>> >> -
>> >>         return 0;
>> >>  }

>> >>                 /* Report the other error interrupts to application */
>> >>                 if (id->err_status) {
>> >>                         cdns_i2c_master_reset(adap);
>> >>
>> >> +                       /* If it is bus arbitration error, try again */
>> >> +                       if (id->err_status & CDNS_I2C_IXR_ARB_LOST) {
>> >> +                               ret = -EAGAIN;
>> >> +                               goto out;
>> >> +                       }
>> >> +

Maybe Just remove Arbitration lost Detect part from  cdns_i2c_process_msg function,  then add to cdns_i2c_master_xfer,  Do you think?

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