@@ -43,6 +43,10 @@ properties:
description:
Desired MDIO bus clock frequency in Hz.
+ suppress-preamble:
+ description: The 32 bit preamble should be suppressed.
+ type: boolean
+
patternProperties:
"^ethernet-phy@[0-9a-f]+$":
type: object
@@ -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 */
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. Suggested-by: Chris Healy <Chris.Healy@zii.aero> Signed-off-by: Andrew Lunn <andrew@lunn.ch> --- Documentation/devicetree/bindings/net/mdio.yaml | 4 ++++ drivers/net/ethernet/freescale/fec_main.c | 9 ++++++++- 2 files changed, 12 insertions(+), 1 deletion(-)