From 7d258451d3454b168ba6df3c9e4cb26a8ce6b752 Mon Sep 17 00:00:00 2001 From: Baruch Siach Date: Mon, 21 Feb 2022 13:45:57 +0200 Subject: [PATCH] net: mdio-ipq4019: add delay after clock enable commit b6ad6261d27708567b309fdb3102b12c42a070cc upstream. Experimentation shows that PHY detect might fail when the code attempts MDIO bus read immediately after clock enable. Add delay to stabilize the clock before bus access. PHY detect failure started to show after commit 7590fc6f80ac ("net: mdio: Demote probed message to debug print") that removed coincidental delay between clock enable and bus access. 10ms is meant to match the time it take to send the probed message over UART at 115200 bps. This might be a far overshoot. Fixes: 23a890d493e3 ("net: mdio: Add the reset function for IPQ MDIO driver") Signed-off-by: Baruch Siach Reviewed-by: Andrew Lunn Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/mdio/mdio-ipq4019.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/net/mdio/mdio-ipq4019.c b/drivers/net/mdio/mdio-ipq4019.c index 5f4cd24a0241d..4eba5a91075c0 100644 --- a/drivers/net/mdio/mdio-ipq4019.c +++ b/drivers/net/mdio/mdio-ipq4019.c @@ -200,7 +200,11 @@ static int ipq_mdio_reset(struct mii_bus *bus) if (ret) return ret; - return clk_prepare_enable(priv->mdio_clk); + ret = clk_prepare_enable(priv->mdio_clk); + if (ret == 0) + mdelay(10); + + return ret; } static int ipq4019_mdio_probe(struct platform_device *pdev)