From 6cb27a04fb779717c4a3d20233b93596885838cf Mon Sep 17 00:00:00 2001
From: Mika Westerberg <mika.westerberg@linux.intel.com>
Date: Thu, 18 Nov 2021 09:06:45 +0200
Subject: [PATCH] thunderbolt: Do not allow subtracting more NFC credits than
configured
References: jsc#SLE-19359
Patch-mainline: v5.17-rc1
Git-commit: 6cb27a04fb779717c4a3d20233b93596885838cf
This might happen if the boot firmware uses different amount of NFC
credits than what the router suggests, or we are dealing with pre-USB4
device.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
drivers/thunderbolt/switch.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index 3014146081c1..463cfdc0b42f 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -623,6 +623,9 @@ int tb_port_add_nfc_credits(struct tb_port *port, int credits)
return 0;
nfc_credits = port->config.nfc_credits & ADP_CS_4_NFC_BUFFERS_MASK;
+ if (credits < 0)
+ credits = max_t(int, -nfc_credits, credits);
+
nfc_credits += credits;
tb_port_dbg(port, "adding %d NFC credits to %lu", credits,
--
2.26.2