Pin C and D are used on C-to-C cable applications including docks,
and for USB-C adapters that convert from DP over USB-C to other
video standards.

Pin Assignment E is intended to be used with adapter from USB-C to DP
plugs or receptacles.

All Chromebook USB-C DFPs support DisplayPort Alternate Mode as the DP
Source with support for all 3 pin assignments. Pin Assignment E is required
in order to support if the user attaches a Pin E C-to-DP cable.

Without this, the displayport.c alt mode driver will error out of
dp_altmode_probe with an -ENODEV, as it cannot find a compatible matching
pin assignment between the DFP_D and UFP_D.

Fixes: dbb3fc0ffa95 ("platform/chrome: cros_ec_typec: Displayport support")

Signed-off-by: Benson Leung <bleung@chromium.org>
Reviewed-by: Jameson Thies <jthies@google.com>
Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
---

Notes:
    v2 - Add Fixes to commit message.

 drivers/platform/chrome/cros_ec_typec.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
index d2228720991f..7678e3d05fd3 100644
--- a/drivers/platform/chrome/cros_ec_typec.c
+++ b/drivers/platform/chrome/cros_ec_typec.c
@@ -22,8 +22,10 @@
 
 #define DRV_NAME "cros-ec-typec"
 
-#define DP_PORT_VDO	(DP_CONF_SET_PIN_ASSIGN(BIT(DP_PIN_ASSIGN_C) | BIT(DP_PIN_ASSIGN_D)) | \
-				DP_CAP_DFP_D | DP_CAP_RECEPTACLE)
+#define DP_PORT_VDO	(DP_CAP_DFP_D | DP_CAP_RECEPTACLE | \
+			 DP_CONF_SET_PIN_ASSIGN(BIT(DP_PIN_ASSIGN_C) | \
+						BIT(DP_PIN_ASSIGN_D) | \
+						BIT(DP_PIN_ASSIGN_E)))
 
 static void cros_typec_role_switch_quirk(struct fwnode_handle *fwnode)
 {
-- 
2.49.0.901.g37484f566f-goog

On Mon, Apr 28, 2025 at 05:48:28PM +0000, Benson Leung wrote:
> Pin C and D are used on C-to-C cable applications including docks,
> and for USB-C adapters that convert from DP over USB-C to other
> video standards.
> 
> Pin Assignment E is intended to be used with adapter from USB-C to DP
> plugs or receptacles.
> 
> [...]

Applied to

    https://git.kernel.org/pub/scm/linux/kernel/git/chrome-platform/linux.git for-next

[1/1] platform/chrome: cros_ec_typec: Set Pin Assignment E in DP PORT VDO
      commit: a9635ef0ca12e7914f42bfa7ca6a019f606c2817

Thanks!