Re: [RFC] ACPI table HID/CID allocation

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 22 November 2017 at 11:30, Daniel Thompson
<daniel.thompson@linaro.org> wrote:
> On 21/11/17 18:10, Udit Kumar wrote:
>>
>> Thanks Ard,
>> For internal SOC devices, this is perfectly ok to drop PRP0001 from CID.
>>
>>> This could be a valid reason to use PRP0001 + compatible, for things like
>>> I2C
>>> slaves that are external to the SoC
>>
>>
>> For external devices (for which HID is not available), you suggest to go
>> with PRP0001 + compatible or that device driver needs add ACPI HID
>> support.
>
>
> I don't think internal or external to the SoC would be any kind of deciding
> factor in how to best to bind, simply because I don't understand why there
> is no HID available.
>

PRP0001 + compatible was invented to avoid the need to allocate a _HID
for each and every component in existence that can already be
identified by a DT compatible string (and little else except, e.g., a
I2C slave address) and is not deeply engrained in the SoC in terms of
clock tree, power states etc. So while internal/external may not be
the most accurate distinction, it is still a useful one IMHO.