While determining the initial pin assignment to be sent in the configure
message, using the DP_PIN_ASSIGN_DP_ONLY_MASK mask causes the DFP_U to
send both Pin Assignment C and E when both are supported by the DFP_U and
UFP_U. The spec (Table 5-7 DFP_U Pin Assignment Selection Mandates,
VESA DisplayPort Alt Mode Standard v2.0) indicates that the DFP_U never
selects Pin Assignment E when Pin Assignment C is offered.
Update the DP_PIN_ASSIGN_DP_ONLY_MASK conditional to intially select only
Pin Assignment C if it is available.
Fixes: 0e3bb7d6894d ("usb: typec: Add driver for DisplayPort alternate mode")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: RD Babiera <rdbabiera@xxxxxxxxxx>
---
drivers/usb/typec/altmodes/displayport.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/altmodes/displayport.c
index 662cd043b50e..8f3e884222ad 100644
--- a/drivers/usb/typec/altmodes/displayport.c
+++ b/drivers/usb/typec/altmodes/displayport.c
@@ -112,8 +112,12 @@ static int dp_altmode_configure(struct dp_altmode *dp, u8 con)
if (dp->data.status & DP_STATUS_PREFER_MULTI_FUNC &&
pin_assign & DP_PIN_ASSIGN_MULTI_FUNC_MASK)
pin_assign &= DP_PIN_ASSIGN_MULTI_FUNC_MASK;
- else if (pin_assign & DP_PIN_ASSIGN_DP_ONLY_MASK)
+ else if (pin_assign & DP_PIN_ASSIGN_DP_ONLY_MASK) {
pin_assign &= DP_PIN_ASSIGN_DP_ONLY_MASK;
+ /* Default to pin assign C if available */
+ if (pin_assign & BIT(DP_PIN_ASSIGN_C))
+ pin_assign = BIT(DP_PIN_ASSIGN_C);
+ }
if (!pin_assign)
return -EINVAL;
base-commit: 97318d6427f62b723c89f4150f8f48126ef74961
--
2.40.0.348.gf938b09366-goog
