Re: [PATCH v3 5/7] usb: dwc3: Add snps,ref-clock-frequency-hz property for ACPI

[Andy Shevchenko]

On Fri, Feb 4, 2022 at 8:44 PM Sean Anderson <sean.anderson@xxxxxxxx> wrote:
> On 2/4/22 1:38 PM, Andy Shevchenko wrote:
> > On Fri, Feb 4, 2022 at 6:00 PM Sean Anderson <sean.anderson@xxxxxxxx> wrote:
> >> On 2/4/22 7:54 AM, Andy Shevchenko wrote:
> >> > On Thursday, January 27, 2022, Sean Anderson <sean.anderson@xxxxxxxx <mailto:sean.anderson@xxxxxxxx>> wrote:

...

> > In order to have more or less unified APIs in the future I would
> > suggest using 'clock-frequency' for the "main" functional clock. For
> > example, 8250_dw uses it for the baud rate generator, while it also
> > utilizes auxiliary clock(s) on some platforms.
>
> OK, I had a look though that driver, and it seems like it uses
> clock-frequency only for the baudclk, and e.g. apb_pclk has no
> corresponding frequency property. For this driver, it would mean that
> the suspend clock would only be configurable through device tree. Is
> that the approach you recommend?


What I meant is to use the "clock-frequency" property as it is kinda
standard de facto for the "main'' functional clock. The rest is up to
the individual drivers. From the API perspective I would expect a
common helper in the future that takes clock name and returns rate
based on clock (if found) or "clock-frequency" property. We may also
extend in far future to support any combinations of the [clock name,
property name] to get a clock rated either via Device Tree or via
ACPI.

-- 
With Best Regards,
Andy Shevchenko