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

From: "[email-masked]" <[email-masked]>
Date: Sat, 16 Feb 2019 15:50:19 +0800

>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.
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