linux-kernel - Re: [PATCH v6 1/7] dt-bindings: i2c: xiic: make clocks optional

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Message-ID: <66c7435c-a936-413e-a016-c860d448c971@amd.com>
Date: Wed, 28 Jan 2026 12:21:41 +0100
From: Michal Simek <michal.simek@....com>
To: Krzysztof Kozlowski <krzk@...nel.org>,
 Abdurrahman Hussain <abdurrahman@...thop.ai>
Cc: Andi Shyti <andi.shyti@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, info@...ean-labs.com,
 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 v6 1/7] dt-bindings: i2c: xiic: make clocks optional

On 1/28/26 11:37, Krzysztof Kozlowski wrote:
> On Tue, Jan 27, 2026 at 09:03:55PM +0000, Abdurrahman Hussain wrote:
>> The xiic driver is designed to operate without explicit clock configuration
> 
> And if you change this in the driver, then you change bindings?
> 
> You miss here explanation based on hardware - how does the hardware work
> if nothing ticks it clocks?

Hardware obviously have clock input which needs to be connected. Without it it 
won't work.
And there are designs like Microblaze one where clock is shared with cpu itself 
and there is no way to adjust it. It is just working.

Then we have configurations where clock is coming from clock generator which 
needs to be enabled. That's case for SOCs with ARM cpus or with clock generators.

This series targets case around PCIe EP. Clock is likely derived from PCIe 
itself and there is no way how to change it, adjust it. It is just running on 
fixed value.

In DT this is design/described via fixed-clock but I expect this concept is not 
used on systems with ACPI.

Thanks,
Michal