linux-kernel - Re: [PATCH v7 1/6] i2c: xiic: skip input clock setup on non-OF systems

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Message-ID: <CAGYn4vxRbPVFvzm1b_mk2KvnRcJSO0Ewmx1tCTEALaZAu+ZQJQ@mail.gmail.com>
Date: Sat, 31 Jan 2026 20:30:40 -0500
From: Abdurrahman Hussain <abdurrahman@...thop.ai>
To: Andy Shevchenko <andriy.shevchenko@...el.com>, 
	Abdurrahman Hussain <abdurrahman@...thop.ai>
Cc: Andrew Lunn <andrew@...n.ch>, Michal Simek <michal.simek@....com>, 
	Andi Shyti <andi.shyti@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	linux-arm-kernel@...ts.infradead.org, linux-i2c@...r.kernel.org, 
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v7 1/6] i2c: xiic: skip input clock setup on non-OF systems

On Sat Jan 31, 2026 at 10:12 AM UTC, Andy Shevchenko wrote:
> On Thu, Jan 29, 2026 at 03:29:45PM -0800, Abdurrahman Hussain wrote:
>> > On Jan 29, 2026, at 2:43 PM, Andrew Lunn <andrew@...n.ch> wrote:
>> > On Thu, Jan 29, 2026 at 09:43:13PM +0000, Abdurrahman Hussain via B4 Relay wrote:
>
>> >> The xiic driver supports operation without explicit clock configuration
>> >> when clocks cannot be specified via firmware, such as on ACPI-based
>> >> systems.
>> >
>> > Are you saying it is technically impossible to specify a clock in
>> > ACPI?
>> >
>> > Maybe a more accurate would be:
>> >
>> > The xiic driver supports operation without explicit clock
>> > configuration when the clocks are not specified via firmware, such as
>> > when the ACPI tables are missing the description of the clocks.
>>
>> Actually, ACPI (since 6.5) added a ClockInput() macro that can be added to
>> _CRS of a device node. The ACPI subsystem in kernel could parse these and
>> convert into proper clocks integrated with the CCF. But, AFAIK, this idea was
>> rejected in the past.
>
> Rejected by which side? CCF?
> Because specification still has that.

I think the argument was that on ACPI based systems clocks are "owned"
by AML and there could be syncronizations issuebetween AML and the OS.

See https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1712165.html