From: Andrew Lunn Date: Sun, 19 Apr 2020 22:04:02 +0000 (+0200) Subject: net: ethernet: fec: Allow the MDIO preamble to be disabled X-Git-Tag: v5.15~3723^2~479^2 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3c01eb62d1bd85a5dd1d22d74339728666ae2c45;p=platform%2Fkernel%2Flinux-starfive.git net: ethernet: fec: Allow the MDIO preamble to be disabled An MDIO transaction normally starts with 32 1s as a preamble. However not all devices requires such a preamble. Add a device tree property which allows the preamble to be suppressed. This will half the size of the MDIO transaction, allowing faster transactions. But it should only be used when all devices on the bus support suppressed preamble. Suggested-by: Chris Healy Signed-off-by: Andrew Lunn Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller --- diff --git a/Documentation/devicetree/bindings/net/mdio.yaml b/Documentation/devicetree/bindings/net/mdio.yaml index ab4a9df8..cd6c6ae 100644 --- a/Documentation/devicetree/bindings/net/mdio.yaml +++ b/Documentation/devicetree/bindings/net/mdio.yaml @@ -45,6 +45,12 @@ properties: defined 2.5MHz should only be used when all devices on the bus support the given clock speed. + suppress-preamble: + description: + The 32 bit preamble should be suppressed. In order for this to + work, all devices on the bus must support suppressed preamble. + type: boolean + patternProperties: "^ethernet-phy@[0-9a-f]+$": type: object diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c index 832a24e..1ae075a 100644 --- a/drivers/net/ethernet/freescale/fec_main.c +++ b/drivers/net/ethernet/freescale/fec_main.c @@ -2064,6 +2064,7 @@ static int fec_enet_mii_init(struct platform_device *pdev) static struct mii_bus *fec0_mii_bus; struct net_device *ndev = platform_get_drvdata(pdev); struct fec_enet_private *fep = netdev_priv(ndev); + bool suppress_preamble = false; struct device_node *node; int err = -ENXIO; u32 mii_speed, holdtime; @@ -2097,8 +2098,11 @@ static int fec_enet_mii_init(struct platform_device *pdev) bus_freq = 2500000; /* 2.5MHz by default */ node = of_get_child_by_name(pdev->dev.of_node, "mdio"); - if (node) + if (node) { of_property_read_u32(node, "clock-frequency", &bus_freq); + suppress_preamble = of_property_read_bool(node, + "suppress-preamble"); + } /* * Set MII speed (= clk_get_rate() / 2 * phy_speed) @@ -2135,6 +2139,9 @@ static int fec_enet_mii_init(struct platform_device *pdev) fep->phy_speed = mii_speed << 1 | holdtime << 8; + if (suppress_preamble) + fep->phy_speed |= BIT(7); + writel(fep->phy_speed, fep->hwp + FEC_MII_SPEED); /* Clear any pending transaction complete indication */