netdev - [PATCH v2] net: davinci_emac: Fix interrupt pacing disable

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Message-Id: <20211101152343.4193233-1-bigunclemax@gmail.com>
Date:   Mon,  1 Nov 2021 18:23:41 +0300
From:   Maxim Kiselev <bigunclemax@...il.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Maxim Kiselev <bigunclemax@...il.com>,
        Grygorii Strashko <grygorii.strashko@...com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Yang Yingliang <yangyingliang@...wei.com>,
        Andrew Lunn <andrew@...n.ch>,
        Colin Ian King <colin.king@...onical.com>,
        Yufeng Mo <moyufeng@...wei.com>,
        Michael Walle <michael@...le.cc>, Sriram <srk@...com>,
        linux-omap@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2] net: davinci_emac: Fix interrupt pacing disable

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@...il.com>
Reviewed-by: Grygorii Strashko <grygorii.strashko@...com>
---
Changes v1 -> v2 (after review of Grygorii Strashko):

 - Simplify !coal->rx_coalesce_usecs handler

---
 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 e8291d8488391..d243ca5dfde00 100644
--- a/drivers/net/ethernet/ti/davinci_emac.c
+++ b/drivers/net/ethernet/ti/davinci_emac.c
@@ -420,8 +420,20 @@ 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;
 
-- 
2.30.2