[PATCH] powerpc: i2c-mpc: make speed registers configurable via FDT
Grant Likely
grant.likely at secretlab.ca
Sun Jul 27 11:25:47 EST 2008
On Fri, Jul 25, 2008 at 05:34:49PM +0200, Wolfgang Grandegger wrote:
> Grant Likely wrote:
>> On Fri, Jul 25, 2008 at 5:04 AM, Wolfgang Grandegger <wg at grandegger.com> wrote:
>>> I was also thinking to just overtake the U-Boot settings if fdt and dfsrr is
>>> not defined for the I2C node (instead of the debatable default values).
>>
>> This is a perfectly valid option. Personally, I'd prefer it encoded
>> in the device tree, but if it looks like a valid speed has already
>> been programmed in then I'm cool with the driver just preserving that.
>> If it turns out to causes problems the we can always change the code
>> to be more conservative later.
>
> How should the Linux driver decide if the registers have been already
> set by the boot-loader? The reset-values might be good as well.
> Therefore, if "clock-frequency" is not specified, the driver may simply
> not touch the fdr and dfsr registers (overtaking the values from the
> boot-loader).
I'm okay with that. If the property isn't present then it is probably
okay to just assume that it is usable.
g.
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