[PATCH 02/24] thunderbolt: Do not try to read UID if DROM offset is read as 0

From: Mika Westerberg
Date: Thu May 18 2017 - 10:41:37 EST


At least Falcon Ridge when in host mode does not have any kind of DROM
available and reading DROM offset returns 0 for these. Do not try to
read DROM any further in that case.

Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Reviewed-by: Yehezkel Bernat <yehezkel.bernat@xxxxxxxxx>
Reviewed-by: Michael Jamet <michael.jamet@xxxxxxxxx>
---
drivers/thunderbolt/eeprom.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/thunderbolt/eeprom.c b/drivers/thunderbolt/eeprom.c
index 6392990c984d..e4e64b130514 100644
--- a/drivers/thunderbolt/eeprom.c
+++ b/drivers/thunderbolt/eeprom.c
@@ -276,6 +276,9 @@ int tb_drom_read_uid_only(struct tb_switch *sw, u64 *uid)
if (res)
return res;

+ if (drom_offset == 0)
+ return -ENODEV;
+
/* read uid */
res = tb_eeprom_read_n(sw, drom_offset, data, 9);
if (res)
--
2.11.0