On Wed, Mar 29, 2023 at 09:51:59PM +0000, RD Babiera wrote:
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
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