[PATCH net-next] liquidio: fix kernel panic when NIC firmware is older than 1.7.2

[Felix Manlunas <felix.manlunas@cavium.com>]

From: Rick Farrington <ricardo.farrington@cavium.com>

Pre-1.7.2 NIC firmware does not support (and does not respond to) the "get
speed" command which is sent by the 1.7.2 driver during modprobe.  Due to a
bug in older firmware (with respect to unknown commands), this unsupported
command causes a cascade of errors that ends in a kernel panic.

Fix it by making the sending of the "get speed" command conditional on the
firmware version.

Signed-off-by: Rick Farrington <ricardo.farrington@cavium.com>
Acked-by: Derek Chickles <derek.chickles@cavium.com>
Signed-off-by: Felix Manlunas <felix.manlunas@cavium.com>
---
Note: To avoid checkpatch.pl "WARNING: line over 80 characters", the comma
      that separates the arguments in the call to strcmp() was placed one
      line below the usual spot.

 drivers/net/ethernet/cavium/liquidio/lio_main.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/cavium/liquidio/lio_main.c b/drivers/net/ethernet/cavium/liquidio/lio_main.c
index 7cb4e75..f83f884 100644
--- a/drivers/net/ethernet/cavium/liquidio/lio_main.c
+++ b/drivers/net/ethernet/cavium/liquidio/lio_main.c
@@ -3671,7 +3671,16 @@ static int setup_nic_devices(struct octeon_device *octeon_dev)
 			OCTEON_CN2350_25GB_SUBSYS_ID ||
 		    octeon_dev->subsystem_id ==
 			OCTEON_CN2360_25GB_SUBSYS_ID) {
-			liquidio_get_speed(lio);
+			/* speed control unsupported in f/w older than 1.7.2 */
+			if (strcmp(octeon_dev->fw_info.liquidio_firmware_version
+			   , "1.7.2") < 0) {
+				dev_info(&octeon_dev->pci_dev->dev,
+					 "speed setting not supported by f/w.");
+				octeon_dev->speed_setting = 25;
+				octeon_dev->no_speed_setting = 1;
+			} else {
+				liquidio_get_speed(lio);
+			}
 
 			if (octeon_dev->speed_setting == 0) {
 				octeon_dev->speed_setting = 25;