[PATCH 3/5] i2c: aspeed: fix master pending state handling

[Tao Ren]

On 10/8/19 3:45 PM, Jae Hyun Yoo wrote:
> Hi Tao,
> 
> On 10/8/2019 3:00 PM, Tao Ren wrote:
>> On 10/7/19 4:13 PM, Jae Hyun Yoo wrote:
>>> In case of master pending state, it should not trigger the master
>>> command because this H/W is sharing the same data buffer for slave
>>> and master operations, so this commit fixes the issue with making
>>> the master command triggering happen when the state goes to active
>>> state.
>>>
>>> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo at linux.intel.com>
>>> ---
>>>   drivers/i2c/busses/i2c-aspeed.c | 9 +++++----
>>>   1 file changed, 5 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
>>> index fa66951b05d0..40f6cf98d32e 100644
>>> --- a/drivers/i2c/busses/i2c-aspeed.c
>>> +++ b/drivers/i2c/busses/i2c-aspeed.c
>>> @@ -336,18 +336,19 @@ static void aspeed_i2c_do_start(struct aspeed_i2c_bus *bus)
>>>       struct i2c_msg *msg = &bus->msgs[bus->msgs_index];
>>>       u8 slave_addr = i2c_8bit_addr_from_msg(msg);
>>>   -    bus->master_state = ASPEED_I2C_MASTER_START;
>>> -
>>>   #if IS_ENABLED(CONFIG_I2C_SLAVE)
>>>       /*
>>>        * If it's requested in the middle of a slave session, set the master
>>>        * state to 'pending' then H/W will continue handling this master
>>>        * command when the bus comes back to the idle state.
>>>        */
>>> -    if (bus->slave_state != ASPEED_I2C_SLAVE_INACTIVE)
>>> +    if (bus->slave_state != ASPEED_I2C_SLAVE_INACTIVE) {
>>>           bus->master_state = ASPEED_I2C_MASTER_PENDING;
>>> +        return;
>>> +    }
>>>   #endif /* CONFIG_I2C_SLAVE */
>>>   +    bus->master_state = ASPEED_I2C_MASTER_START;
>>>       bus->buf_index = 0;
>>>         if (msg->flags & I2C_M_RD) {
>>> @@ -432,7 +433,7 @@ static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
>>>           if (bus->slave_state != ASPEED_I2C_SLAVE_INACTIVE)
>>>               goto out_no_complete;
>>>   -        bus->master_state = ASPEED_I2C_MASTER_START;
>>> +        aspeed_i2c_do_start(bus);
>>>       }
>>
>> Shall we move the restart-master logic from master_irq to bus_irq? The reason being:
>> master transaction cannot be restarted when aspeed-i2c is running in slave state and
>> receives STOP interrupt, because aspeed_i2c_master_irq won't be called in this case.
> 
> Even in that case, master can be restarted properly because slave_irq
> will be called first because master is in MASTER_PENDING state, so the
> slave_irq handles the STOP interrupt as well, and then master_irq will
> be called with SLAVE_INACTIVE state so the aspeed_i2c_do_start can be
> called eventually.

I mean master_irq cannot be called when irq_remaining becomes 0 after slave_irq.


Cheers,

Tao