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

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Message-ID: <885561e7-ef1e-172d-fe39-7b9effecf175@linux.intel.com>
Date:   Fri, 17 Mar 2017 15:29:17 +0200
From:   Jarkko Nikula <jarkko.nikula@...ux.intel.com>
To:     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 03/17/17 13:24, Luis Oliveira wrote:
> 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.
>
I'm fine with it. I think it's more understandable.

-- 
Jarkko