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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aXoul5n9sA1UmqoS@smile.fi.intel.com>
Date: Wed, 28 Jan 2026 17:43:19 +0200
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Michal Simek <michal.simek@....com>
Cc: Andrew Lunn <andrew@...n.ch>, Krzysztof Kozlowski <krzk@...nel.org>,
	Abdurrahman Hussain <abdurrahman@...thop.ai>,
	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,
	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 Wed, Jan 28, 2026 at 04:00:30PM +0100, Michal Simek wrote:
> On 1/28/26 15:45, Andy Shevchenko wrote:
> > On Wed, Jan 28, 2026 at 03:34:02PM +0100, Andrew Lunn wrote:
> > > On Wed, Jan 28, 2026 at 12:21:41PM +0100, Michal Simek wrote:
> > > > 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.
> > > 
> > > Should ACPI potential limitations be making the DT description less
> > > accurate?
> > > 
> > > Would it not be better that the driver has an DT binding and an ACPI
> > > binding? Where there are common properties, common functions can be
> > > used to retrieve them. However, if ACPI lacks usable clocks, use the
> > > of_ method to get the clock from DT, and skip it for ACPI.
> > 
> > Why should we use of_ methods? If this is required we can check the type of
> > fwnode and act accordingly, but I think this should go deeper into some
> > treewide available helpers, because now some drivers repeat the mantra.
> > 
> > But how do the driver get the clock frequency (if needed for some register
> > settings and/or calculations)? DT seems to have well established property
> > 'clock-frequency' for that. Can we consider it as "ACPI binding" as well?
> 
> "clock-frequency" property in i2c is used for selecting i2c speed 100/400kHz.
> 
> Clock frequency in this driver is about describing clock coming to IP itself.
> Documentation/devicetree/bindings/i2c/xlnx,xps-iic-2.00.a.yaml

Ah, I see, then is_of_node() probably is the compromise how to deal with
this setup.

-- 
With Best Regards,
Andy Shevchenko