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@xxxxxxxxxxxxxxx
> Signed-off-by: RD Babiera <rdbabiera@xxxxxxxxxx>
Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> ---
> 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
--
heikki
