[PATCH 4.20 073/183] net: stmmac: Check if CBS is supported before configuring

[Greg Kroah-Hartman]

4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 0650d4017f4d2eee67230a02285a7ae5204240c2 ]

Check if CBS is currently supported before trying to configure it in HW.

Cc: Joao Pinto <jpinto@xxxxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Giuseppe Cavallaro <peppe.cavallaro@xxxxxx>
Cc: Alexandre Torgue <alexandre.torgue@xxxxxx>
Signed-off-by: Jose Abreu <joabreu@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
index 531294f4978bc..58ea18af9813a 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
@@ -301,6 +301,8 @@ static int tc_setup_cbs(struct stmmac_priv *priv,
 	/* Queue 0 is not AVB capable */
 	if (queue <= 0 || queue >= tx_queues_count)
 		return -EINVAL;
+	if (!priv->dma_cap.av)
+		return -EOPNOTSUPP;
 	if (priv->speed != SPEED_100 && priv->speed != SPEED_1000)
 		return -EOPNOTSUPP;
 
-- 
2.19.1