Subject: Re: [PATCH v4 3/3] powerpc: doc/dts-bindings: update doc of FSL I2C bindings

From: Wolfgang Grandegger <[email-masked]>
Date: Tue, 09 Feb 2010 20:23:04 +0100

Wolfgang Grandegger wrote:
> Hi Grant,
> 
> Grant Likely wrote:
>> On Thu, Jan 28, 2010 at 6:25 AM, Wolfgang Grandegger <[email-masked]> wrote:
>>> From: Wolfgang Grandegger <[email-masked]>
>>>
>>> This patch adds the MPC5121 to the list of supported devices,
>>> enhances the doc of the "clock-frequency" property and removes
>>> the obsolete "cell-index" property from the example nodes.
>>> Furthermore and example for the MPC5121 has been added.
>>>
>>> Signed-off-by: Wolfgang Grandegger <[email-masked]>
>> Thanks Wolfgang.  Comments below.
>>
>>> ---
>>>  Documentation/powerpc/dts-bindings/fsl/i2c.txt |   30 +++++++++++++++++++----
>>>  1 files changed, 24 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/Documentation/powerpc/dts-bindings/fsl/i2c.txt b/Documentation/powerpc/dts-bindings/fsl/i2c.txt
>>> index b6d2e21..2f62dae 100644
>>> --- a/Documentation/powerpc/dts-bindings/fsl/i2c.txt
>>> +++ b/Documentation/powerpc/dts-bindings/fsl/i2c.txt
>>> @@ -9,8 +9,9 @@ Recommended properties :
>>>
>>>  - compatible : compatibility list with 2 entries, the first should
>>>    be "fsl,CHIP-i2c" where CHIP is the name of a compatible processor,
>>> -   e.g. mpc8313, mpc8543, mpc8544, mpc5200 or mpc5200b. The second one
>>> -   should be "fsl-i2c".
>>> +   e.g. mpc8313, mpc8543, mpc8544, mpc5121, mpc5200 or mpc5200b. The
>>> +   second one should be "fsl-i2c". For the mpc5121, an additional node
>>> +   "fsl,mpc5121-i2c-ctrl" is required as shown in the example below.
>> While you're editing this line; drop the requirement for the second
>> value to be 'fsl-i2c'.  We don't use it anymore, and only preserve it
>> for backwards compatibility with old trees.
> 
> OK.
> 
>>>  - interrupts : <a b> where a is the interrupt number and b is a
>>>    field that represents an encoding of the sense and level
>>>    information for the interrupt.  This should be encoded based on
>>> @@ -20,29 +21,46 @@ Recommended properties :
>>>    services interrupts for this device.
>>>  - fsl,preserve-clocking : boolean; if defined, the clock settings
>>>    from the bootloader are preserved (not touched).
>>> - - clock-frequency : desired I2C bus clock frequency in Hz.
>>> + - clock-frequency : desired I2C bus clock frequency in Hz.  If this
>>> +   property and "fsl,preserve-clocking" is not defined, a safe fixed
>>> +   clock divider value is used (resulting in a small clock frequency).
>> Nah, leave this as is.  Don't make it sound like omitting both
>> properties is a valid option.  The driver may (and should!) handle the
>> situation gracefully, but that fact does not need to be documented.
> 
> The safe value is not a good choice, indeed. Then it will also change
> MPC_I2C_CLOCK_SAFE to MPC_I2C_CLOCK_LEGACY in i2c-mpc.c.
> 
> I will also fix the other issues you commented on.

And I will also remove the "device_type" line from:

 -------------
 Required properties :

 - device_type : Should be "i2c"
 - reg : Offset and length of the register set for the device
 -------------

Wolfgang.