Commit 30cd2cb1 authored by Mark Pearson's avatar Mark Pearson Committed by Greg Kroah-Hartman
Browse files

usb: typec: ucsi: Handle incorrect num_connectors capability 



The UCSI spec states that the num_connectors field is 7 bits, and the
8th bit is reserved and should be set to zero.
Some buggy FW has been known to set this bit, and it can lead to a
system not booting.
Flag that the FW is not behaving correctly, and auto-fix the value
so that the system boots correctly.

Found on Lenovo P1 G8 during Linux enablement program. The FW will
be fixed, but seemed worth addressing in case it hit platforms that
aren't officially Linux supported.

Signed-off-by: default avatarMark Pearson <mpearson-lenovo@squebb.ca>
Reviewed-by: default avatarHeikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20250821185319.2585023-1-mpearson-lenovo@squebb.ca


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 5570ad14

drivers/usb/typec/ucsi/ucsi.c

+6 −0
Original line number Diff line number Diff line
@@ -1807,6 +1807,12 @@ static int ucsi_init(struct ucsi *ucsi) 
		ret = -ENODEV;

		goto err_reset;

	}

	/* Check if reserved bit set. This is out of spec but happens in buggy FW */

	if (ucsi->cap.num_connectors & 0x80) {

		dev_warn(ucsi->dev, "UCSI: Invalid num_connectors %d. Likely buggy FW\n",

			 ucsi->cap.num_connectors);

		ucsi->cap.num_connectors &= 0x7f; // clear bit and carry on

	}



	/* Allocate the connectors. Released in ucsi_unregister() */

	connector = kcalloc(ucsi->cap.num_connectors + 1, sizeof(*connector), GFP_KERNEL);