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

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Date:   Mon, 1 Nov 2021 17:03:56 +0300
From:   Maxim Kiselev <bigunclemax@...il.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Grygorii Strashko <grygorii.strashko@...com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, Andrew Lunn <andrew@...n.ch>,
        Yang Yingliang <yangyingliang@...wei.com>,
        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: Re: [PATCH] net: davinci_emac: Fix interrupt pacing disable

>From ca26bf62366f249a2ed360b00c1883652848bfdc Mon Sep 17 00:00:00 2001
From: Maxim Kiselev <bigunclemax@...il.com>
Date: Mon, 1 Nov 2021 16:37:12 +0300
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>
---
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