Re: [PATCH v2 2/2] usb: typec: ucsi: acpi: Assume UCSI 1.2 on Lenovo ThinkPad T14 Gen 2a

["Mark Pearson" <mpearson-lenovo@squebb.ca>]

On Fri, Nov 6, 2026, at 11:54 AM, Heikki Krogerus wrote:
> On Tue, Nov 03, 2026 at 05:10:21PM +0100, Stanisław Titenko via B4 Relay wrote:
>> 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.
>> 
>> Use the zero version quirk for the ThinkPad T14 Gen 2a, matching the
>> two board names of this model (20XK and 20XL).
>
> So is the product family the same?
>
> Could you use DMI_MATCH(DMI_PRODUCT_FAMILY... instead of adding
> separate matches entry for both?
>

The board names are what I recommended - they are pretty safe to guarantee they won't change whereas other fields are less guaranteed (guidance given by FW team). It is annoying there are two I know.

FWIW I would rather wait for confirmation from the FW team if they will fix this before accepting the quirk. I am still waiting for a reply from them though I'm afraid.

>> Tested on a ThinkPad T14 Gen 2a (20XK) 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>
>
> Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
>
>> ---
>>  drivers/usb/typec/ucsi/ucsi_acpi.c | 16 ++++++++++++++++
>>  1 file changed, 16 insertions(+)
>> 
>> diff --git a/drivers/usb/typec/ucsi/ucsi_acpi.c b/drivers/usb/typec/ucsi/ucsi_acpi.c
>> index 47ba0e15b8ba..d752fc7b61ec 100644
>> --- a/drivers/usb/typec/ucsi/ucsi_acpi.c
>> +++ b/drivers/usb/typec/ucsi/ucsi_acpi.c
>> @@ -196,6 +196,22 @@ static const struct dmi_system_id ucsi_acpi_quirks[] = {
>>  		},
>>  		.driver_data = (void *)&ucsi_zero_version_ops,
>>  	},
>> +	{
>> +		/* Lenovo ThinkPad T14 Gen 2a */
>> +		.matches = {
>> +			DMI_MATCH(DMI_BOARD_VENDOR, "LENOVO"),
>> +			DMI_MATCH(DMI_BOARD_NAME, "20XK"),
>> +		},
>> +		.driver_data = (void *)&ucsi_zero_version_ops,
>> +	},
>> +	{
>> +		/* Lenovo ThinkPad T14 Gen 2a */
>> +		.matches = {
>> +			DMI_MATCH(DMI_BOARD_VENDOR, "LENOVO"),
>> +			DMI_MATCH(DMI_BOARD_NAME, "20XL"),
>> +		},
>> +		.driver_data = (void *)&ucsi_zero_version_ops,
>> +	},
>>  	{
>>  		.matches = {
>>  			DMI_MATCH(DMI_SYS_VENDOR, "LG Electronics"),
>> 
>> -- 
>> 2.56.0
>> 
>
> -- 
> heikki