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Date:   Mon, 16 Aug 2021 20:09:38 +0200
From:   Ben Hutchings <ben.hutchings@mind.be>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 4/5] net: dsa: microchip: ksz8795: Fix VLAN untagged
 flag change on deletion
Message-ID: <20210816180938.GH18930@cephalopod>
References: <20210816174905.GD18930@cephalopod>
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commit af01754f9e3c553a2ee63b4693c79a3956e230ab upstream.

When a VLAN is deleted from a port, the flags in struct
switchdev_obj_port_vlan are always 0.  ksz8_port_vlan_del() copies the
BRIDGE_VLAN_INFO_UNTAGGED flag to the port's Tag Removal flag, and
therefore always clears it.

In case there are multiple VLANs configured as untagged on this port -
which seems useless, but is allowed - deleting one of them changes the
remaining VLANs to be tagged.

It's only ever necessary to change this flag when a VLAN is added to
the port, so leave it unchanged in ksz8_port_vlan_del().

Fixes: e66f840c08a2 ("net: dsa: ksz: Add Microchip KSZ8795 DSA driver")
Signed-off-by: Ben Hutchings <ben.hutchings@mind.be>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backport to 5.10: adjust context]
Signed-off-by: Ben Hutchings <ben.hutchings@mind.be>
---
 drivers/net/dsa/microchip/ksz8795.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/net/dsa/microchip/ksz8795.c b/drivers/net/dsa/microchip/ksz8795.c
index b4b164d75520..8f2b54ae57f2 100644
--- a/drivers/net/dsa/microchip/ksz8795.c
+++ b/drivers/net/dsa/microchip/ksz8795.c
@@ -895,7 +895,6 @@ static void ksz8795_port_vlan_add(struct dsa_switch *ds, int port,
 static int ksz8795_port_vlan_del(struct dsa_switch *ds, int port,
 				 const struct switchdev_obj_port_vlan *vlan)
 {
-	bool untagged = vlan->flags & BRIDGE_VLAN_INFO_UNTAGGED;
 	struct ksz_device *dev = ds->priv;
 	u16 data, vid, pvid;
 	u8 fid, member, valid;
@@ -904,8 +903,6 @@ static int ksz8795_port_vlan_del(struct dsa_switch *ds, int port,
 	ksz_pread16(dev, port, REG_PORT_CTRL_VID, &pvid);
 	pvid = pvid & 0xFFF;
 
-	ksz_port_cfg(dev, port, P_TAG_CTRL, PORT_REMOVE_TAG, untagged);
-
 	for (vid = vlan->vid_begin; vid <= vlan->vid_end; vid++) {
 		ksz8795_r_vlan_table(dev, vid, &data);
 		ksz8795_from_vlan(data, &fid, &member, &valid);
-- 
2.20.1