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authorRD Babiera <rdbabiera@google.com>2023-03-29 21:51:59 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2023-04-05 19:20:12 +0200
commiteddebe39602efe631b83ff8d03f26eba12cfd760 (patch)
tree6538b34575b322caedfd7979fb16ef7abb74ceef /drivers
parentec799c8a92e0be91e0940cc739a27f483242df65 (diff)
usb: typec: altmodes/displayport: Fix configure initial pin assignment
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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/usb/typec/altmodes/displayport.c6
1 files changed, 5 insertions, 1 deletions
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;