[U-Boot] [PATCH] net: fec_mxc: fix mii_speed configuration for MX6's

[Philippe De Muyter]

On MX6DL at least, measured mdc speed was wrong (3.3 Mhz instead of 2.5
Mhz), because of wrong assumptions about the reference clock and the
way the divider is used.

I have fixed that for all MX6's by using the IPG clock as the reference
clock, and applying the - 1 correction when we have a ENET MAC instead
of a FEC MAC, just like what is done in the fec linux driver.

Signed-off-by: Philippe De Muyter <phdm at macqel.be>
---
 drivers/net/fec_mxc.c |   20 +++++++++++++++++---
 1 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/net/fec_mxc.c b/drivers/net/fec_mxc.c
index 3b2b995..3ab0ecd 100644
--- a/drivers/net/fec_mxc.c
+++ b/drivers/net/fec_mxc.c
@@ -124,13 +124,27 @@ static int fec_mdio_read(struct ethernet_regs *eth, uint8_t phyAddr,
 
 static void fec_mii_setspeed(struct ethernet_regs *eth)
 {
+	u32 sysclock;
+	u32 mii_speed;
+
 	/*
 	 * Set MII_SPEED = (1/(mii_speed * 2)) * System Clock
 	 * and do not drop the Preamble.
+	 * shift the result by 1, because MII_SPEED field is at bits 6..1.
 	 */
-	writel((((imx_get_fecclk() / 1000000) + 2) / 5) << 1,
-			&eth->mii_speed);
-	debug("%s: mii_speed %08x\n", __func__, readl(&eth->mii_speed));
+#if defined(CONFIG_MX6)
+	sysclock = mxc_get_clock(MXC_IPG_CLK);
+#else
+	sysclock = imx_get_fecclk();
+#endif
+#define MIIM_SPEED 2500000
+	mii_speed = DIV_ROUND_UP(sysclock, (MIIM_SPEED * 2));
+#ifdef FEC_QUIRK_ENET_MAC
+	mii_speed -= 1;
+#endif
+	writel(mii_speed << 1, &eth->mii_speed);
+	debug("%s: sysclock %u, mii_speed %08x\n", __func__, sysclock,
+						readl(&eth->mii_speed));
 }
 
 static int fec_mdio_write(struct ethernet_regs *eth, uint8_t phyAddr,
-- 
1.7.5.3