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

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Message-Id: <2428D892-89F9-4013-9681-AD9BD76B0874@nexthop.ai>
Date: Thu, 29 Jan 2026 15:29:45 -0800
From: Abdurrahman Hussain <abdurrahman@...thop.ai>
To: Andrew Lunn <andrew@...n.ch>
Cc: 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>,
 Andy Shevchenko <andriy.shevchenko@...el.com>,
 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 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:
>> From: Abdurrahman Hussain <abdurrahman@...thop.ai>
>> 
>> 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.
> 
> Andrew

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. So, technically, it's the kernel that lacks support on
ACPI systems.

What about this wording then:

The xiic driver supports operation without explicit clock configuration when
the clocks specified via firmware are ignored, such as on ACPI systems.

Abdurrahman