From 245ee9f8d97e9eea8b99ab3c56ac8249cc256fec Mon Sep 17 00:00:00 2001
From: Vincent Palatin <vpalatin@chromium.org>
Date: Wed, 27 May 2015 09:32:38 -0700
Subject: [PATCH] pd: never answer malformed VDM

When we are receiving a VDM which seems malformed, don't try to send an
answer, else we can ping-pong broken messages with the other side.

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>

BRANCH=none
BUG=none
TEST=plug Ryu P6 to plankton, no longer see endless "ERR:CMDT:1" error
messages.

Change-Id: If5b581c5c68996c60e37ac6d96638fd5df24356f
Reviewed-on: https://chromium-review.googlesource.com/273525
Reviewed-by: Todd Broch <tbroch@chromium.org>
Tested-by: Vincent Palatin <vpalatin@chromium.org>
Reviewed-by: Alec Berg <alecaberg@chromium.org>
Commit-Queue: Vincent Palatin <vpalatin@chromium.org>
---
 common/usb_pd_policy.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/common/usb_pd_policy.c b/common/usb_pd_policy.c
index 36ecba8fc6..19c69a7369 100644
--- a/common/usb_pd_policy.c
+++ b/common/usb_pd_policy.c
@@ -726,6 +726,8 @@ int pd_svdm(int port, int cnt, uint32_t *payload, uint32_t **rpayload)
 #endif /* CONFIG_USB_PD_ALT_MODE_DFP */
 	} else {
 		CPRINTF("ERR:CMDT:%d\n", cmd);
+		/* do not answer */
+		rsize = 0;
 	}
 	return rsize;
 }