linux-kernel - Re: [PATCH v9 6/7] i2c: xiic: use numbered adapter registration

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 for Android: free password hash cracker in your pocket

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

Message-Id: <DF13B121-56F2-4987-A47B-99A20E18554E@nexthop.ai>
Date: Tue, 3 Feb 2026 10:50:44 -0800
From: Abdurrahman Hussain <abdurrahman@...thop.ai>
To: Andrew Lunn <andrew@...n.ch>
Cc: Andy Shevchenko <andriy.shevchenko@...el.com>,
 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 v9 6/7] i2c: xiic: use numbered adapter registration



> On Feb 3, 2026, at 10:31 AM, Andrew Lunn <andrew@...n.ch> wrote:
> 
> On Tue, Feb 03, 2026 at 10:14:49AM -0800, Abdurrahman Hussain wrote:
>> 
>> 
>>> On Feb 3, 2026, at 7:45 AM, Andy Shevchenko <andriy.shevchenko@...el.com> wrote:
>>> 
>>> On Mon, Feb 02, 2026 at 08:37:23PM +0000, Abdurrahman Hussain via B4 Relay wrote:
>>> 
>>>> Use i2c_add_numbered_adapter() to allow platform devices to specify
>>>> fixed bus numbers when needed.
>>> 
>>> Not sure about this. Doesn't it break the current approach? Please, double
>>> check that.
>>> 
>>> -- 
>>> With Best Regards,
>>> Andy Shevchenko
>>> 
>>> 
>> 
>> If pdev->id is PLATFORM_DEVID_NONE(-1) then i2c_add_numbered_adapter()
>> falls back to dynamic allocation and calls i2c_add_adapter().
>> 
>> Many existing i2c drivers use the same approach, see i2c-pxa.c and
>> i2c-pnx.c etc.
> 
> It is not about if other drivers do this. Its about does this change
> the behaviour of this driver, so that I2C busses get different IDs
> then before, and so cause regressions?
> 
> You need to explain in the commit message why you think this is safe.
> 
>    Andrew

Before, the driver was always doing the dynamic allocation due to
i2c_add_adapter(). So there could not have been a system that relied on
consistent i2c bus numbering. Even between reboots bus numbering could change.

The systems that did set pdev->id and were expecting a consistent i2c bus
numbering were broken to begin with.

This patch won’t break any existing systems or cause regressions.