From: sashiko-bot@kernel.org
To: "Stanisław Titenko" <kernel@resetko.pl>
Cc: linux-usb@vger.kernel.org
Subject: Re: [PATCH] usb: typec: ucsi: acpi: Assume UCSI 1.0 on Lenovo ThinkPad T14 Gen 2a
Date: Sat, 31 Oct 2026 21:43:39 +0000 [thread overview]
Message-ID: <sashiko-outbox-192184@kernel.org> (raw)
In-Reply-To: <20261031-ucsi-lenovo-t14g2a-v1-1-183751e63c02@resetko.pl>
> From: Stanisław Titenko <kernel@resetko.pl>
>
> The Lenovo ThinkPad T14 Gen 2a exposes a functional UCSI ACPI PPM but
> the firmware leaves the VERSION field of the UCSI mailbox at zero.
>
> ucsi_register() rejects a zero version with -ENODEV, leaving the
> system without registered USB Type-C connectors. Without an OPM, the
> embedded controller does not complete DisplayPort Alternate Mode setup
> when a USB-C dock or monitor that supplies power is connected after
> boot, so the display stays dark while USB and charging work.
>
> The mailbox uses the 48-byte UCSI 1.x layout, and the PPM works
> correctly when UCSI 1.0 is assumed.
>
> Add a DMI-specific UCSI operation for the ThinkPad T14 Gen 2a that
> substitutes UCSI 1.0 only when firmware reports a zero version.
> Preserve any valid non-zero firmware version.
>
> Tested on a ThinkPad T14 Gen 2a with BIOS 1.33 (R1MET63W): both
> Type-C connectors register, and plugging and replugging a USB-C
> monitor with an integrated hub and power delivery brings up
> DisplayPort Alternate Mode each time.
>
> Reported-by: Daniel Dev <daniel.dev@noex.uk>
> Closes: https://lore.kernel.org/linux-usb/b1Wn_eFvTFShGbd970WWl4CWhge_6P2x7Wb6rab3QHNlE4OJ4p__O-QN3B6I-308ftr5oV5Zr7vywA0vdvmtNw6E0YJnVM2ek_5DcFnkXB0=@noex.uk/
> Fixes: c1b0bc2dabfa ("usb: typec: Add support for UCSI interface")
> Cc: stable@vger.kernel.org
> Assisted-by: pi:claude-opus-5-5
> Signed-off-by: Stanisław Titenko <kernel@resetko.pl>
Sashiko has reviewed this patch and found no issues.
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261031-ucsi-lenovo-t14g2a-v1-1-183751e63c02@resetko.pl?part=1
next prev parent reply other threads:[~2026-10-31 21:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-31 21:40 [PATCH] usb: typec: ucsi: acpi: Assume UCSI 1.0 on Lenovo ThinkPad T14 Gen 2a Stanisław Titenko via B4 Relay
2026-10-31 21:43 ` sashiko-bot [this message]
2026-11-01 22:50 ` Mark Pearson
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