[PATCH net] net: enetc: fix the incorrect clearing of IF_MODE bits

The enetc phylink .mac_config handler intends to clear the IFMODE field
(bits 1:0) of the PM0_IF_MODE register, but incorrectly clears all the
other fields instead.

For normal operation, the bug was inconsequential, due to the fact that
we write the PM0_IF_MODE register in two stages, first in
phylink .mac_config (which incorrectly cleared out a bunch of stuff),
then we update the speed and duplex to the correct values in
phylink .mac_link_up.

Judging by the code (not tested), it looks like maybe loopback mode was
broken, since this is one of the settings in PM0_IF_MODE which is
incorrectly cleared.

Fixes: c76a97218dcb ("net: enetc: force the RGMII speed and duplex instead of operating in inband mode")
Reported-by: Pavel Machek (CIP) <redacted>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
 drivers/net/ethernet/freescale/enetc/enetc_pf.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/freescale/enetc/enetc_pf.c b/drivers/net/ethernet/freescale/enetc/enetc_pf.c
index f0ff95096846..8c6fa1345996 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc_pf.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc_pf.c

@@ -541,8 +541,7 @@ static void enetc_mac_config(struct enetc_hw *hw, phy_interface_t phy_mode)
 
 	if (phy_interface_mode_is_rgmii(phy_mode)) {
 		val = enetc_port_rd(hw, ENETC_PM0_IF_MODE);
-		val &= ~ENETC_PM0_IFM_EN_AUTO;
-		val &= ENETC_PM0_IFM_IFMODE_MASK;
+		val &= ~(ENETC_PM0_IFM_EN_AUTO | ENETC_PM0_IFM_IFMODE_MASK);
 		val |= ENETC_PM0_IFM_IFMODE_GMII | ENETC_PM0_IFM_RG;
 		enetc_port_wr(hw, ENETC_PM0_IF_MODE, val);
 	}

-- 
2.25.1

Hello:

This patch was applied to netdev/net.git (refs/heads/master):

On Thu, 23 Sep 2021 16:23:33 +0300 you wrote:

The enetc phylink .mac_config handler intends to clear the IFMODE field
(bits 1:0) of the PM0_IF_MODE register, but incorrectly clears all the
other fields instead.

For normal operation, the bug was inconsequential, due to the fact that
we write the PM0_IF_MODE register in two stages, first in
phylink .mac_config (which incorrectly cleared out a bunch of stuff),
then we update the speed and duplex to the correct values in
phylink .mac_link_up.

[...]

Here is the summary with links:
  - [net] net: enetc: fix the incorrect clearing of IF_MODE bits
    https://git.kernel.org/netdev/net/c/325fd36ae76a

You are awesome, thank you!
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