Re: [PATCH 04/12] i3c: master: Support ACPI enumeration

On Thu, 19 Mar 2026 10:29:38 -0400, Frank Li wrote:
> On Wed, Mar 18, 2026 at 10:57:17PM +0530, Akhil R wrote:
>> Support ACPI enumeration for I2C and I3C devices on an I3C bus.
>> Read _ADR and LVR from the ACPI resources and extract the data
> 
> ADR have _, but not _ before LVR, I am not familary with ACPI.

'_ADR' is a static ACPI object (or method), but LVR is not.
LVR (Legacy Virtual Register) has to be read by parsing the
ACPI I2C serial resource.

> 
>> as per the ACPI specification for an I3C bus. Also read
>> mipi-i3c-static-address as per the MIPI DISCO specifications [1]
>> to get the static address to be used.
>>
>> Although the existing subsystem allows host controllers to register
>> through the ACPI table, it was not possible to describe I3C or I2C
>> devices there.
> 
> why?

The existing code relied on the 'reg' property to get PID, static address etc.
ACPI table entries do not use reg property, instead use _ADR or other resource
objects. Also for ACPI, MIPI recommends a different format which encodes the
details in the _ADR object. The specification also includes a few additional
properties like mipi-i3c-static-address, mipi-i3c-static-method etc. which
the new code follows.

> 
>> This change enables describing the I3C or I2C devices
> 
> Don't use "This commit/change/" just Enable ...

Ack. Will update.

Best Regards,
Akhil