drm/bridge: ps8640: Add software to support aux defer

This chip can not handle aux defer if the host directly program
its aux registers to access edid/dpcd. So we need let software
to handle the aux defer situation.
Signed-off-by: Jason Yen <jason.yen@paradetech.corp-partner.google.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220930042506.2529522-1-jason.yen@paradetech.corp-partner.google.com

drivers/gpu/drm/bridge/parade-ps8640.c

@@ -286,7 +286,6 @@ static ssize_t ps8640_aux_transfer_msg(struct drm_dp_aux *aux,
 	}
 
 	switch (data & SWAUX_STATUS_MASK) {
-	/* Ignore the DEFER cases as they are already handled in hardware */
 	case SWAUX_STATUS_NACK:
 	case SWAUX_STATUS_I2C_NACK:
 		/*
@@ -303,6 +302,14 @@ static ssize_t ps8640_aux_transfer_msg(struct drm_dp_aux *aux,
 	case SWAUX_STATUS_ACKM:
 		len = data & SWAUX_M_MASK;
 		break;
+	case SWAUX_STATUS_DEFER:
+	case SWAUX_STATUS_I2C_DEFER:
+		if (is_native_aux)
+			msg->reply |= DP_AUX_NATIVE_REPLY_DEFER;
+		else
+			msg->reply |= DP_AUX_I2C_REPLY_DEFER;
+		len = data & SWAUX_M_MASK;
+		break;
 	case SWAUX_STATUS_INVALID:
 		return -EOPNOTSUPP;
 	case SWAUX_STATUS_TIMEOUT: