[PATCH 4.19 221/323] net: davinci_emac: Fix interrupt pacing disable

[Greg Kroah-Hartman]

From: Maxim Kiselev <bigunclemax@xxxxxxxxx>

[ Upstream commit d52bcb47bdf971a59a2467975d2405fcfcb2fa19 ]

This patch allows to use 0 for `coal->rx_coalesce_usecs` param to
disable rx irq coalescing.

Previously we could enable rx irq coalescing via ethtool
(For ex: `ethtool -C eth0 rx-usecs 2000`) but we couldn't disable
it because this part rejects 0 value:

       if (!coal->rx_coalesce_usecs)
               return -EINVAL;

Fixes: 84da2658a619 ("TI DaVinci EMAC : Implement interrupt pacing functionality.")
Signed-off-by: Maxim Kiselev <bigunclemax@xxxxxxxxx>
Reviewed-by: Grygorii Strashko <grygorii.strashko@xxxxxx>
Link: https://lore.kernel.org/r/20211101152343.4193233-1-bigunclemax@xxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/ethernet/ti/davinci_emac.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/ti/davinci_emac.c b/drivers/net/ethernet/ti/davinci_emac.c
index 56130cf293f37..566da1e3cfbcc 100644
--- a/drivers/net/ethernet/ti/davinci_emac.c
+++ b/drivers/net/ethernet/ti/davinci_emac.c
@@ -426,8 +426,20 @@ static int emac_set_coalesce(struct net_device *ndev,
 	u32 int_ctrl, num_interrupts = 0;
 	u32 prescale = 0, addnl_dvdr = 1, coal_intvl = 0;
 
-	if (!coal->rx_coalesce_usecs)
-		return -EINVAL;
+	if (!coal->rx_coalesce_usecs) {
+		priv->coal_intvl = 0;
+
+		switch (priv->version) {
+		case EMAC_VERSION_2:
+			emac_ctrl_write(EMAC_DM646X_CMINTCTRL, 0);
+			break;
+		default:
+			emac_ctrl_write(EMAC_CTRL_EWINTTCNT, 0);
+			break;
+		}
+
+		return 0;
+	}
 
 	coal_intvl = coal->rx_coalesce_usecs;
 
-- 
2.33.0