linux-kernel - Re: [RESEND PATCH v6 5/6] i2c: designware: add SLAVE mode functions

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Date:   Fri, 17 Mar 2017 11:24:03 +0000
From:   Luis Oliveira <Luis.Oliveira@...opsys.com>
To:     Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Luis Oliveira <Luis.Oliveira@...opsys.com>,
        <wsa@...-dreams.de>, <robh+dt@...nel.org>, <mark.rutland@....com>,
        <andriy.shevchenko@...ux.intel.com>,
        <mika.westerberg@...ux.intel.com>, <linux-i2c@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <Ramiro.Oliveira@...opsys.com>, <Joao.Pinto@...opsys.com>,
        <CARLOS.PALMINHA@...opsys.com>
Subject: Re: [RESEND PATCH v6 5/6] i2c: designware: add SLAVE mode functions

On 02-Mar-17 15:17, Luis Oliveira wrote:
> On 02-Mar-17 14:33, Jarkko Nikula wrote:
>> On 03/01/17 17:59, Luis Oliveira wrote:
>>> - Changes in Kconfig to enable I2C_DESIGNWARE_SLAVE support
>>> - Slave functions added to core library file
>>> - Slave abort sources added to common source file
>>> - New driver: i2c-designware-slave added
>>> - Changes in the Makefile to compile the I2C_DESIGNWARE_SLAVE module
>>>   when supported by the architecture.
>>>
>>> All the SLAVE flow is added but it is not enabled via platform
>>> driver.
>>>
>>> Signed-off-by: Luis Oliveira <lolivei@...opsys.com>
>>> ---
>>> V5->V6
>>> - Enable Slave mode using a different option (kbuild reported an error)
>>> - Identation fixes needed
>>> - Changed debug prints to dev_vdbg
>>> - Fixed slave enumeration
>>>
>>>  drivers/i2c/busses/Kconfig                 |  14 +-
>>>  drivers/i2c/busses/Makefile                |   1 +
>>>  drivers/i2c/busses/i2c-designware-common.c |   7 +
>>>  drivers/i2c/busses/i2c-designware-core.h   |   3 +
>>>  drivers/i2c/busses/i2c-designware-slave.c  | 403 +++++++++++++++++++++++++++++
>>>  5 files changed, 427 insertions(+), 1 deletion(-)
>>>  create mode 100644 drivers/i2c/busses/i2c-designware-slave.c
>>>
>> ...
>>> diff --git a/drivers/i2c/busses/i2c-designware-common.c
>>> b/drivers/i2c/busses/i2c-designware-common.c
>>> index 6357c7c78f6d..24641635aa20 100644
>>> --- a/drivers/i2c/busses/i2c-designware-common.c
>>> +++ b/drivers/i2c/busses/i2c-designware-common.c
>>> @@ -56,6 +56,13 @@ static char *abort_sources[] = {
>>>          "trying to use disabled adapter",
>>>      [ARB_LOST] =
>>>          "lost arbitration",
>>> +    [ABRT_SLAVE_FLUSH_TXFIFO] =
>>> +        "read command so flush old data in the TX FIFO",
>>> +    [ABRT_SLAVE_ARBLOST] =
>>> +        "slave lost the bus while transmitting data to a remote master",
>>> +    [ABRT_SLAVE_RD_INTX] =
>>> +        "slave request for data to be transmitted and there is a 1 in "
>>> +        "bit 8 of IC_DATA_CMD",
>>>  };
>>
>> I know ABRT_SLAVE_RD_INTX case is from the specification but I would prefer here
>> one-line error text so it will be easier to grep from sources.
>>
>> I would like it to be also be more understandable. I don't know did I understood
>> it correctly but does it occur when attempting to read controller while
>> transmitting or something like that?
> 
> It happens in the "slave-transmitter" mode, when the processor side responds to
> a request for data to be transmitted and at the same time someone writes 1 to
> the bit 8 of the IC_DATA_CMD. This bit in "slave-transmitter" mode has to be "0"
> to indicate the data is to be transmitted.
> 
> In "slave-receiver" mode it has no purpose since writes to this register are not
> required.

If you agree for the v7 I can change it to "incorrect slave-transmitter mode
configuration", it's not as clear but it gives a clue of where the error comes from.

> 
>>
>>> diff --git a/drivers/i2c/busses/i2c-designware-core.h
>>> b/drivers/i2c/busses/i2c-designware-core.h
>>> index b620d76ffc8d..6c70945cccea 100644
>>> --- a/drivers/i2c/busses/i2c-designware-core.h
>>> +++ b/drivers/i2c/busses/i2c-designware-core.h
>>> @@ -277,6 +277,7 @@ struct dw_i2c_dev {
>>>      void            (*disable)(struct dw_i2c_dev *dev);
>>>      void            (*disable_int)(struct dw_i2c_dev *dev);
>>>      int            (*init)(struct dw_i2c_dev *dev);
>>> +    bool            mode;
>>>  };
>>>
>>
>> As I mentioned add here comment for "mode" not in patch 4/6.
>>
> Ok, I will.
> Thanks.
>