netdev - [PATCH v3] ravb: implement MTU change while device is up

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Message-Id: <1566327686-8996-1-git-send-email-uli+renesas@fpond.eu>
Date:   Tue, 20 Aug 2019 21:01:26 +0200
From:   Ulrich Hecht <uli+renesas@...nd.eu>
To:     linux-renesas-soc@...r.kernel.org
Cc:     netdev@...r.kernel.org, davem@...emloft.net,
        sergei.shtylyov@...entembedded.com, niklas.soderlund@...natech.se,
        wsa@...-dreams.de, horms@...ge.net.au, magnus.damm@...il.com,
        geert@...der.be, Ulrich Hecht <uli+renesas@...nd.eu>
Subject: [PATCH v3] ravb: implement MTU change while device is up

Uses the same method as various other drivers: shut the device down,
change the MTU, then bring it back up again.

Tested on Renesas D3 Draak and M3-W Salvator-X boards.

Signed-off-by: Ulrich Hecht <uli+renesas@...nd.eu>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@...natech.se>
Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
Reviewed-by: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
---

Hi!

This revision reverts the MTU change if re-opening the device fails.

CU
Uli


 drivers/net/ethernet/renesas/ravb_main.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index ef8f089..402bcec 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -1810,12 +1810,24 @@ static int ravb_do_ioctl(struct net_device *ndev, struct ifreq *req, int cmd)
 
 static int ravb_change_mtu(struct net_device *ndev, int new_mtu)
 {
+	unsigned int old_mtu = ndev->mtu;
+
 	if (netif_running(ndev))
-		return -EBUSY;
+		ravb_close(ndev);
 
 	ndev->mtu = new_mtu;
 	netdev_update_features(ndev);
 
+	if (netif_running(ndev)) {
+		int err = ravb_open(ndev);
+
+		if (err) {
+			ndev->mtu = old_mtu;
+			netdev_update_features(ndev);
+			return err;
+		}
+	}
+
 	return 0;
 }
 
-- 
2.7.4