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

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Message-ID: <d6183e8c-5ff8-32c9-44ff-bef038ee0baa@synopsys.com>
Date:   Thu, 2 Mar 2017 15:17:43 +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 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.

> 
>> 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.