Subject: Re: [PATCH RFC 2/2] clk: scmi: Add support for two #clock-cells to pass rate rounding mode

From: Peng Fan <[email-masked]>
Date: Thu, 23 Apr 2026 21:12:13 +0800

On Thu, Apr 23, 2026 at 09:25:42AM +0100, Sudeep Holla wrote:
>On Thu, Apr 23, 2026 at 09:17:47AM +0800, Peng Fan wrote:
[...]
>> 
>> My question is: if the firmware were to select divider 3 and produce
>> 96,333,333 Hz (only ~0.13% higher than the request), would that be
>> considered a violation of ROUND_DOWN semantics, or is ROUND_DOWN intended
>> to select the closest achievable output frequency rather than enforcing
>> a strict inequality against the requested rate?
>> 
>
>We can change the driver to default to ROUND_AUTO if that helps. I fully
>understand the default ROUND_DOWN is not good but if firmware can't handle
>your use case with ROUND_AUTO, it is firmware issue.

Thanks for the suggestion.

Switching the default to ROUND_AUTO could indeed resolve the video clock
configuration issue we are seeing.

I understand the concern that if firmware cannot handle a given use-case
correctly with ROUND_AUTO, then it is fundamentally a firmware issue rather
than something to be worked around in the OS.

I will check internally with our firmware team to confirm whether using
ROUND_AUTO as the default is safe and applicable for all clocks supported
on our platforms.

Thanks,
Peng

>-- 
>Regards,
>Sudeep