[U-Boot] [PATCH 1/4] mx6sx: pins: Enable SION for I2C3 iomux setting

[Li Ye-B37916]

Hi Stefano, Nikolay,

On 1/30/2015 1:54 AM, Stefano Babic wrote:
> Hi,
>
> On 12/01/2015 11:37, Nikolay Dimitrov wrote:
>> Hi Ye.Li,
>>
>> On 01/12/2015 10:46 AM, Ye.Li wrote:
>>> The I2C SDA and SCL require the IOMUX SION bit set to get input signal.
>>>
>>> Signed-off-by: Ye.Li <B37916 at freescale.com>
>>> ---
>>>   arch/arm/include/asm/arch-mx6/mx6sx_pins.h |    4 ++--
>>>   1 files changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/arch/arm/include/asm/arch-mx6/mx6sx_pins.h
>>> b/arch/arm/include/asm/arch-mx6/mx6sx_pins.h
>>> index 7c6c1e8..da8c698 100644
>>> --- a/arch/arm/include/asm/arch-mx6/mx6sx_pins.h
>>> +++ b/arch/arm/include/asm/arch-mx6/mx6sx_pins.h
>>> @@ -420,7 +420,7 @@ enum {
>>>
>>>        MX6_PAD_KEY_COL4__KPP_COL_4                            =
>>> IOMUX_PAD(0x03FC, 0x00B4, 0, 0x0000, 0, 0),
>>>        MX6_PAD_KEY_COL4__ENET2_MDC                            =
>>> IOMUX_PAD(0x03FC, 0x00B4, 1, 0x0000, 0, 0),
>>> -     MX6_PAD_KEY_COL4__I2C3_SCL                             =
>>> IOMUX_PAD(0x03FC, 0x00B4, 2, 0x07B8, 2, 0),
>>> +     MX6_PAD_KEY_COL4__I2C3_SCL                             =
>>> IOMUX_PAD(0x03FC, 0x00B4, IOMUX_CONFIG_SION | 2, 0x07B8, 2, 0),
>>>        MX6_PAD_KEY_COL4__USDHC2_LCTL                          =
>>> IOMUX_PAD(0x03FC, 0x00B4, 3, 0x0000, 0, 0),
>>>        MX6_PAD_KEY_COL4__AUDMUX_AUD5_RXC                      =
>>> IOMUX_PAD(0x03FC, 0x00B4, 4, 0x0664, 0, 0),
>>>        MX6_PAD_KEY_COL4__GPIO2_IO_14                          =
>>> IOMUX_PAD(0x03FC, 0x00B4, 5, 0x0000, 0, 0),
>>> @@ -467,7 +467,7 @@ enum {
>>>
>>>        MX6_PAD_KEY_ROW4__KPP_ROW_4                            =
>>> IOMUX_PAD(0x0410, 0x00C8, 0, 0x0000, 0, 0),
>>>        MX6_PAD_KEY_ROW4__ENET2_MDIO                           =
>>> IOMUX_PAD(0x0410, 0x00C8, 1, 0x0770, 3, 0),
>>> -     MX6_PAD_KEY_ROW4__I2C3_SDA                             =
>>> IOMUX_PAD(0x0410, 0x00C8, 2, 0x07BC, 2, 0),
>>> +     MX6_PAD_KEY_ROW4__I2C3_SDA                             =
>>> IOMUX_PAD(0x0410, 0x00C8, IOMUX_CONFIG_SION | 2, 0x07BC, 2, 0),
>>>        MX6_PAD_KEY_ROW4__USDHC1_LCTL                          =
>>> IOMUX_PAD(0x0410, 0x00C8, 3, 0x0000, 0, 0),
>>>        MX6_PAD_KEY_ROW4__AUDMUX_AUD5_RXFS                     =
>>> IOMUX_PAD(0x0410, 0x00C8, 4, 0x0668, 0, 0),
>>>        MX6_PAD_KEY_ROW4__GPIO2_IO_19                          =
>>> IOMUX_PAD(0x0410, 0x00C8, 5, 0x0000, 0, 0),
>>>
>> Usually the SCL is output-only, driven by the I2C master. Why do you
>> need to enable SION bit on SCL, if the pin will be used as output-only?
>>
> Right - I do not see why SION should be set.
>
> Regards,
> Stefano Babic
>

Setting SION to both SDA and SCL is required by i.MX6 reference manual.  You can find the information below from i2c chapter.

34.2 External Signals
This section discusses I2C signals that connect off-chip.
For I2C compliance, all devices connected to the I2Cn_SCL and I2Cn_SDA signals must
have open-drain or open-collector outputs. The logic AND function is implemented on
both lines with external pull-up resistors.
Inputs of I2Cn_SCL and I2Cn_SDA also need to be manually enabled by setting the
SION bit in the IOMUX after the corresponding PADs are selected as I2C function.

Best regards,
Ye Li