[PATCH] usb: typec: altmodes/displayport: Fix probe pin assign check

From: Prashant Malani
Date: Wed Feb 08 2023 - 15:53:45 EST


While checking Pin Assignments of the port and partner during probe, we
don't take into account whether the peripheral is a plug or receptacle.

This manifests itself in a mode entry failure on certain docks and
dongles with captive cables. For instance, the Startech.com Type-C to DP
dongle (Model #CDP2DP) advertises its DP VDO as 0x405. This would fail
the Pin Assignment compatibility check, despite it supporting
Pin Assignment C as a UFP.

Update the check to use the correct DP Pin Assign macros that
take the peripheral's receptacle bit into account.

Fixes: c1e5c2f0cb8a ("usb: typec: altmodes/displayport: correct pin assignment for UFP receptacles")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Diana Zigterman <dzigterman@xxxxxxxxxxxx>
Signed-off-by: Prashant Malani <pmalani@xxxxxxxxxxxx>
---

I realize this is a bit late in the release cycle, but figured since it
is a fix it might still be considered. Please let me know if it's too
late and I can re-send this after the 6.3-rc1 is released. Thanks!

drivers/usb/typec/altmodes/displayport.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/altmodes/displayport.c
index 20db51471c98..662cd043b50e 100644
--- a/drivers/usb/typec/altmodes/displayport.c
+++ b/drivers/usb/typec/altmodes/displayport.c
@@ -547,10 +547,10 @@ int dp_altmode_probe(struct typec_altmode *alt)
/* FIXME: Port can only be DFP_U. */

/* Make sure we have compatiple pin configurations */
- if (!(DP_CAP_DFP_D_PIN_ASSIGN(port->vdo) &
- DP_CAP_UFP_D_PIN_ASSIGN(alt->vdo)) &&
- !(DP_CAP_UFP_D_PIN_ASSIGN(port->vdo) &
- DP_CAP_DFP_D_PIN_ASSIGN(alt->vdo)))
+ if (!(DP_CAP_PIN_ASSIGN_DFP_D(port->vdo) &
+ DP_CAP_PIN_ASSIGN_UFP_D(alt->vdo)) &&
+ !(DP_CAP_PIN_ASSIGN_UFP_D(port->vdo) &
+ DP_CAP_PIN_ASSIGN_DFP_D(alt->vdo)))
return -ENODEV;

ret = sysfs_create_group(&alt->dev.kobj, &dp_altmode_group);
--
2.39.1.519.gcb327c4b5f-goog