r8169: improve interrupt coalescing parameter handling

The chip supports only frame limits 0, 4, 8, .. 60 internally.
Returning EINVAL for all val % 4 != 0 seems to be a little bit too
unfriendly to the user. Therefore round up the frame limit to the next
supported value. In addition round up the time limit, else a very low
limit could be rounded down to 0, and interpreted as "ignore value"
by the chip.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index 6c17c234bc068e2be6512155fce9813f4e870665..a81d46abe3c21bde285b0571f5025eb71b9aeb95 100644 (file)
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -1909,21 +1909,21 @@ static int rtl_set_coalesce(struct net_device *dev, struct ethtool_coalesce *ec)
                 * - then user does `ethtool -C eth0 rx-usecs 100`
                 *
                 * since ethtool sends to kernel whole ethtool_coalesce
-                * settings, if we do not handle rx_usecs=!0, rx_frames=1
-                * we'll reject it below in `frames % 4 != 0`.
+                * settings, if we want to ignore rx_frames then it has
+                * to be set to 0.
                 */
                if (p->frames == 1) {
                        p->frames = 0;
                }
 
-               units = p->usecs * 1000 / scale;
-               if (p->frames > RTL_COALESCE_FRAME_MAX || p->frames % 4)
-                       return -EINVAL;
+               units = DIV_ROUND_UP(p->usecs * 1000, scale);
+               if (p->frames > RTL_COALESCE_FRAME_MAX)
+                       return -ERANGE;
 
                w <<= RTL_COALESCE_SHIFT;
                w |= units;
                w <<= RTL_COALESCE_SHIFT;
-               w |= p->frames >> 2;
+               w |= DIV_ROUND_UP(p->frames, 4);
        }
 
        rtl_lock_work(tp);