Re: [PATCH] usb: typec: altmode: Fix altmode to handle multiple parners

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

Hi,

On Thu, Apr 02, 2026 at 02:04:32PM +0200, François Scala wrote:
> From: François Scala <francois@scala.name>
> 
> The partner field in the altmode struct is a single pointer and the sysfs
> symlink uses a fixed name. This cause an error when a second partner is
> registered.
> 
>   sysfs: cannot create duplicate filename '/devices/platform/USBC000:00/typec/port0/port0.0/partner'

I think what you seeing here is either a bug in our ucsi driver, or
(more likely) a problem in the firmware.

> The field is replaced by an array of pointers and the symlink use the
> device name to avoid conflict.
> 
>   /sys/devices/platform/USBC000:00/typec/port0/port0.0/
>   lrwxrwxrwx 1 root root    0 Apr  2 09:12 port0-partner.0 -> ../port0-partner/port0-partner.0
>   lrwxrwxrwx 1 root root    0 Apr  2 09:12 port0-partner.1 -> ../port0-partner/port0-partner.1

No. You can not have more than a single partner per mode. Let's figure
out the root issue. Please check the svids of the partner altmodes:

        grep . /sys/class/typec/port0-partner/port0-partner.*/svid

Then provide the trace output from the ucsi driver, dmesg output
(full), and also acpidump of your system. The ucsi trace you can
get like this (assuming you have the debugfs mounted at
/sys/kernel/debug):

        cd /sys/kernel/debug/tracing
        echo 1 > events/ucsi/enable
        # plug-in your device
        # wait for a few seconds
        cat trace

For acpidump you need the acpica-tools installed:

        acpidump -o my_acpi.dump

thanks,

-- 
heikki