Re: [EXTERNAL] [PATCH v1 1/1] i2c: designware: Add ACPI ID MSFT0006 for Microsoft Cobalt SoCs

[Andy Shevchenko]

On Sun, Nov 08, 2026 at 11:45:00AM +0100, Wolfram Sang wrote:
> 
> > For Cobalt, the firmware exposes the designware input clock frequency
> > through the ACPI HCLK object.
> > Is there an existing way to retrieve or configure this clock frequency
> > through the ACPI tables, rather than hardcoding it in the driver?
> 
> Calling for Andy here for being the designware + ACPI expert.

We don't have the common way, it's unspecified. However, many drivers and some
firmwares adopted the "clock-frequency" property. Unfortunately for I2C it means
the clock of the bus, and not functional clock of the controller. So, I'm
afraid you will need to have your own custom solution. Also makes sense to look
what ARM people do in the same situtions (I know that Qualcomm tries hard to
enable ACPI on laptops, if I was you, I would ask them first).

-- 
With Best Regards,
Andy Shevchenko