linux-kernel - Re: [PATCH RESEND v3 1/6] i3c: mipi-i3c-hci: Add MIPI0100 ACPI ID to the I3C Support List

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Message-ID: <ZrYlNOjFQE9dHsVV@smile.fi.intel.com>
Date: Fri, 9 Aug 2024 17:18:28 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Jarkko Nikula <jarkko.nikula@...ux.intel.com>
Cc: Shyam Sundar S K <Shyam-sundar.S-k@....com>,
	Alexandre Belloni <alexandre.belloni@...tlin.com>,
	Guruvendra Punugupati <Guruvendra.Punugupati@....com>,
	Krishnamoorthi M <krishnamoorthi.m@....com>,
	linux-i3c@...ts.infradead.org, linux-kernel@...r.kernel.org,
	"Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH RESEND v3 1/6] i3c: mipi-i3c-hci: Add MIPI0100 ACPI ID to
 the I3C Support List

On Fri, Aug 09, 2024 at 04:54:18PM +0300, Jarkko Nikula wrote:
> Hi
> 
> I Cc'ed Andy and Rafael because of ACPI ID allocation question that came to
> my mind below which I'm not expert enough to answer.
> 
> On 8/7/24 8:23 AM, Shyam Sundar S K wrote:
> > The current driver code lacks the necessary plumbing for ACPI IDs,
> > preventing the mipi-i3c-hci driver from being loaded on x86
> > platforms that advertise I3C ACPI support.
> > 
> > This update adds the MIPI0100 ACPI ID to the list of supported IDs.

When adding a new ACPI ID, always provide the following information:

1) link (in some form) to the official confirmation / documentation for
the allocated ID by the vendor (MIPI in this case) _OR_ (very exceptional!)
why the bad ID had been allocated;

2) are there devices in the wild (on the market) that use the being added ID(s)?

3) excerpt from the device (independently if it's public already, see above,
or not) DSDT ACPI table.

With the given patch it looks to me that you most likely need a local, AMD
specific ID as well.

So, in my ideal world the DSDT should be like

	Device (I3CC)
	{
		Name (_HID, "...") // AMD specific _HID
		Name (_CID, "MIPI0100") // Compatible ID for generic I3C controller
		...
	}

Is this the case? Why not?

P.S. Make sure you Cc me on ACPI ID matters in the future.

-- 
With Best Regards,
Andy Shevchenko