linux-kernel - Re: [PATCH v2 1/3] usb: typec: ucsi: Detect and skip duplicate altmodes from buggy firmware

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Message-ID: <aUpkXs3Jd6UDoPuq@kuha>
Date: Tue, 23 Dec 2025 11:43:58 +0200
From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To: "Chia-Lin Kao (AceLan)" <acelan.kao@...onical.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
	Fedor Pchelkin <boddah8794@...il.com>,
	Andrei Kuchynski <akuchynski@...omium.org>,
	Venkat Jayaraman <venkat.jayaraman@...el.com>,
	Myrrh Periwinkle <myrrhperiwinkle@...labs.xyz>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] usb: typec: ucsi: Detect and skip duplicate
 altmodes from buggy firmware

Hi,

Mon, Nov 17, 2025 at 11:00:34AM +0200, Heikki Krogerus kirjoitti:
> Hi,
> 
> Tue, Nov 11, 2025 at 09:05:39AM +0800, Chia-Lin Kao (AceLan) kirjoitti:
> > Some firmware implementations incorrectly return the same altmode
> > multiple times at different offsets when queried via UCSI_GET_ALTERNATE_MODES.
> > This causes sysfs duplicate filename errors and kernel call traces when
> > the driver attempts to register the same altmode twice:
> > 
> >   sysfs: cannot create duplicate filename '/devices/.../typec/port0/port0.0/partner'
> >   typec-thunderbolt port0-partner.1: failed to create symlinks
> >   typec-thunderbolt port0-partner.1: probe with driver typec-thunderbolt failed with error -17
> > 
> > Detect duplicate altmodes by comparing SVID and VDO before registration.
> > If a duplicate is detected, skip it and print a single clean warning
> > message instead of generating a kernel call trace:
> > 
> >   ucsi_acpi USBC000:00: con2: Firmware bug: duplicate partner altmode SVID 0x8087 (VDO 0x8087a043 vs 0x00000001) at offset 1, ignoring. Please update your system firmware.
> > 
> > This makes the error handling more user-friendly while still alerting
> > users to the firmware bug.
> > 
> > The duplicate detection logic is implemented in a reusable helper
> > function ucsi_altmode_is_duplicate() and used in ucsi_register_altmodes().
> > The fix applies to all three recipient types: partner (SOP), port (CON),
> > and plug (SOP_P) altmodes.

Will you be sending v3? This does need a fix.

thanks,

-- 
heikki