[PATCH net-next 7/7] r8169: add check for invalid parameter combination in rtl_set_coalesce

[Heiner Kallweit]

Realtek provided information about a HW constraint that time limit must
not be set to 0 if the frame limit is >0. Add a check for this and
reject invalid parameter combinations.

Signed-off-by: Heiner Kallweit <hkallwe...@gmail.com>
---
 drivers/net/ethernet/realtek/r8169_main.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c 
b/drivers/net/ethernet/realtek/r8169_main.c
index 3fef1b254..0ac3976e3 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -1908,6 +1908,11 @@ static int rtl_set_coalesce(struct net_device *dev, 
struct ethtool_coalesce *ec)
        if (tx_fr == 1)
                tx_fr = 0;
 
+       /* HW requires time limit to be set if frame limit is set */
+       if ((tx_fr && !ec->tx_coalesce_usecs) ||
+           (rx_fr && !ec->rx_coalesce_usecs))
+               return -EINVAL;
+
        w |= FIELD_PREP(RTL_COALESCE_TX_FRAMES, DIV_ROUND_UP(tx_fr, 4));
        w |= FIELD_PREP(RTL_COALESCE_RX_FRAMES, DIV_ROUND_UP(rx_fr, 4));
 
-- 
2.26.2