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From:   Michael Walle <michael@walle.cc>
To:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Nicolas Ferre <nicolas.ferre@microchip.com>,
        Claudiu Beznea <claudiu.beznea@microchip.com>,
        "David S . Miller" <davem@davemloft.net>,
        Michael Walle <michael@walle.cc>
Subject: [PATCH] net: macb: ignore tx_clk if MII is used
Date:   Wed, 20 Jan 2021 20:43:03 +0100
Message-Id: <20210120194303.28268-1-michael@walle.cc>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

If the MII interface is used, the PHY is the clock master, thus don't
set the clock rate. On Zynq-7000, this will prevent the following
warning:
  macb e000b000.ethernet eth0: unable to generate target frequency: 25000000 Hz

Signed-off-by: Michael Walle <michael@walle.cc>
---
 drivers/net/ethernet/cadence/macb_main.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 814a5b10141d..472bf8f220bc 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -470,6 +470,10 @@ static void macb_set_tx_clk(struct macb *bp, int speed)
 	if (!bp->tx_clk || (bp->caps & MACB_CAPS_CLK_HW_CHG))
 		return;
 
+	/* In case of MII the PHY is the clock master */
+	if (bp->phy_interface == PHY_INTERFACE_MODE_MII)
+		return;
+
 	switch (speed) {
 	case SPEED_10:
 		rate = 2500000;
-- 
2.20.1