diff options
| -rw-r--r-- | drivers/net/fec_mxc.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/drivers/net/fec_mxc.c b/drivers/net/fec_mxc.c index 79f6737..798cc16 100644 --- a/drivers/net/fec_mxc.c +++ b/drivers/net/fec_mxc.c @@ -131,13 +131,25 @@ static void fec_mii_setspeed(struct ethernet_regs *eth) /* * Set MII_SPEED = (1/(mii_speed * 2)) * System Clock * and do not drop the Preamble. + * + * The i.MX28 and i.MX6 types have another field in the MSCR (aka + * MII_SPEED) register that defines the MDIO output hold time. Earlier + * versions are RAZ there, so just ignore the difference and write the + * register always. + * The minimal hold time according to IEE802.3 (clause 22) is 10 ns. + * HOLDTIME + 1 is the number of clk cycles the fec is holding the + * output. + * The HOLDTIME bitfield takes values between 0 and 7 (inclusive). + * Given that ceil(clkrate / 5000000) <= 64, the calculation for + * holdtime cannot result in a value greater than 3. */ - register u32 speed = DIV_ROUND_UP(imx_get_fecclk(), 5000000); + u32 pclk = imx_get_fecclk(); + u32 speed = DIV_ROUND_UP(pclk, 5000000); + u32 hold = DIV_ROUND_UP(pclk, 100000000) - 1; #ifdef FEC_QUIRK_ENET_MAC speed--; #endif - speed <<= 1; - writel(speed, ð->mii_speed); + writel(speed << 1 | hold << 8, ð->mii_speed); debug("%s: mii_speed %08x\n", __func__, readl(ð->mii_speed)); } |