Re: [PATCH V2] clk: introduce u-boot,ignore-clk-defaults

[Sean Anderson <seanga2@gmail.com>]

On 10/28/21 10:10 PM, Tom Rini wrote:
> On Fri, Oct 29, 2021 at 09:28:01AM +0800, Peng Fan (OSS) wrote:
>> From: Peng Fan <peng.fan@nxp.com>
>>
>> Current code has a force clk_set_defaults in multiple stages,
>> U-Boot reuse the same device tree and Linux Kernel device tree,
>> but we not register all the clks as Linux Kernel, so clk_set_defaults
>> will fail and cause the clk provider registeration fail.
>>
>> So introduce a new property to ignore the default settings which could
>> be used by any node that wanna ignore default settings.
>>
>> Reviewed-by: Simon Glass <sjg@chromium.org>
>> Signed-off-by: Peng Fan <peng.fan@nxp.com>
>> ---
>>
>> V2:
>>   Add R-b tag
>>   Tom, Simon
>>     After a thought, I think still put it as a u-boot thing. assigned-clock-x is
>>     actually Linux specific, however I could not add the new property to Linux,
>>     because we are supporting SystemReady-IR, we need the assigned-clock-x property
>>     in linux working and ignore it in U-Boot.
> 
> OK, right, so... it should be a generic property to say what, early
> firmware should ignore this clock unless otherwise required and use the
> preconfigured value?
> 

The issue is that for platforms sharing devicetrees between U-Boot and
Linux, Linux may add assigned-clocks which are not implemented in
U-Boot. Although assigning a specific frequency or parent to a clock may
not be necessary to use the device, it will fail to probe because the
clock cannot be found. I believe this property is intended for these
cases.

--Sean