linux-kernel - Re: [PATCH 5/6] platform/chrome: cros_ec_lpc: Correct ACPI name for Framework Laptop

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Date: Mon, 27 May 2024 19:06:40 +0100
From: Ben Walsh <ben@...nut.com>
To: Tzung-Bi Shih <tzungbi@...nel.org>
Cc: Benson Leung <bleung@...omium.org>, Guenter Roeck <groeck@...omium.org>,
 "Dustin L. Howett" <dustin@...ett.net>, Kieran Levin <ktl@...me.work>,
 Thomas Weißschuh <linux@...ssschuh.net>, Mario Limonciello
 <mario.limonciello@....com>, chrome-platform@...ts.linux.dev,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/6] platform/chrome: cros_ec_lpc: Correct ACPI name for
 Framework Laptop

Tzung-Bi Shih <tzungbi@...nel.org> writes:

> On Fri, May 24, 2024 at 07:35:22PM +0100, Ben Walsh wrote:

>> I could add a new quirk which provides an alternative ACPI match table
>> to be used instead of the default. In the default case the match_table
>> will contain only "GOOG0004" as before. But in the Framework EC case the
>> match table will be "PNP0C09".
>
> I think it doesn't work as the current quirk is handling in
> cros_ec_lpc_probe() which is after matching.

I was thinking of a new quirk called CROS_EC_LPC_QUIRK_ACPI_MATCH, and
putting it in cros_ec_lpc_init(), not cros_ec_lpc_probe(). Do we have to
do all quirk handling in cros_ec_lpc_probe()?

> My original idea: would it be possible to get the `adev` in cros_ec_lpc_probe()
> via any lookup API?  If yes, it could still use DMI match and get `adev` if
> required.

That works; I've tested it.

In this scenario we're not using the existing PNP0C09 platform device,
which means I can't look at
/sys/bus/acpi/devices/PNP0C09\:00/physical_node/driver and see the
driver. Is this OK?

(Note that ACPI_COMPANION_SET() doesn't fix this. You can use
acpi_bind_one() but that seems more like internal plumbing).