[PATCH v6] i2c-gpio: add devicetree support

Grant Likely grant.likely at secretlab.ca
Fri Feb 25 13:07:44 EST 2011


Okay.
On Feb 24, 2011 7:04 PM, "Thomas Chou" <thomas at wytron.com.tw> wrote:
>
> Hi Grant,
>
>
> On 02/25/2011 12:22 AM, Grant Likely wrote:
>>>
>>> +Required properties:
>>> +- compatible : should be "i2c-gpio".
>>> +- gpios : should specify GPIOs used for SDA and SCL lines, in that
order.
>>> +Optional properties:
>>> +- sda-is-open-drain : present if SDA gpio is open-drain.
>>> +- scl-is-open-drain : present if SCL gpio is open-drain.
>>> +- scl-is-output-only : present if the output driver for SCL cannot be
>>> +       turned off. this will prevent clock stretching from working.
>>> +- speed-hz : SCL frequency.
>>
>>
>> Hi Thomas,
>>
>> One nitpick; I just looked, and other i2c controllers are already
>> using 'clock-frequency' instead of 'speed-hz' for the speed of the
>> bus.  I'd like to see this patch use the same terminology.
>
>
> I studied 'clock-frequency' usage of existing i2c drivers before working
on this patch.
>
> i2c-ibm_iic.c, i2c-mpc.c, i2c-ocores.c : use as bus clock frequency input
to the core.
>
> i2c-cpm.c : use as i2c SCL output frequency.
>
> Most other non-i2c drivers use clock-frequency as bus clock frequency
input, too.
>
> I think the SCL freq usage in i2c-cpm.c is confusing. So I would suggest
we borrow 'speed-hz' from spi subsystem, which means the clock freq output
on the peripheral bus.

Okay.

g.

>
> Best regards,
> Thomas
>
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