From eddebe39602efe631b83ff8d03f26eba12cfd760 Mon Sep 17 00:00:00 2001
From: RD Babiera <rdbabiera@google.com>
Date: Wed, 29 Mar 2023 21:51:59 +0000
Subject: [PATCH] usb: typec: altmodes/displayport: Fix configure initial pin
assignment
Git-commit: eddebe39602efe631b83ff8d03f26eba12cfd760
References: git-fixes
Patch-mainline: v6.3-rc6
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@vger.kernel.org
Signed-off-by: RD Babiera <rdbabiera@google.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20230329215159.2046932-1-rdbabiera@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
drivers/usb/typec/altmodes/displayport.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/drivers/usb/typec/altmodes/displayport.c
+++ b/drivers/usb/typec/altmodes/displayport.c
@@ -104,8 +104,12 @@ static int dp_altmode_configure(struct d
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
+ 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;