tx51 ethernet regression

Eric Bénard eric at eukrea.com
Mon Jul 16 07:44:06 EDT 2012

Hi Christian,

Le Mon, 16 Jul 2012 13:28:13 +0200,
Christian Kapeller <christian.kapeller at cmotion.eu> a écrit :
> I recently came to update my barebox port based on the karo tx51 imx
> module from v2012.03.0 to v2012.07.0.
> I discovered, that, when trying to use the ethernet connection, I more
> often than not get frame errors reported by the FEC.
> --snip--
> barebox at Ka-Ro tx51:/ dhcp
> phy0: Link is up - 1000/Full
> error frame: 0x97b961c0 0x00000890
> error frame: 0x97b96188 0x00000882
> DHCP client bound to address
> --snap--
> The errors range from 'non octet aligned frame' over 'Fifo overrun' to
> timeouts. It renders the ethernet support unusable. Small images may
> work but, require the one and other retry.
> One thing that catches my eye is that the auto negotioation resulted in
> a 1000MBit link. The imx fec does only support 100MBit. I forced the
> link to be set to 10MBit by declaring xcv_type=MII10 in the
> fec_platform_data structure. Interestingly the link is now reported as
> 100MBit, and shows the same behaviour.
> Another thing I checked was the changed pad definitions in commit
> 2bdc9f57a86dff41cfc1f87b644a2e53fdcce2b6. Not only the type of the pad
> data structure changed, but also some of their configuration as well.
> For example, pads that were configured with FEC_PAD_CTL, now have other
> settings enabled.
> I'reverted the pad changes, but still no luck. Auto negtiation starts,
> but I don't seem to get any packets.
> So my question is: What change since v2012.03.0 could cause this kind of
> behaviour?
same problem here. the problem comes from :
68b32be4926d3ab5b72036c0ceecef2f82aa0625 "i.MX51: Synchronize iomux
header file from kernel"
as now most pins have NO_PAD_CTRL which means the pad doesn't get
reconfigured and thus some pads to communicate with the FEC are no more

A dirty workaround to default PAD config is :
diff --git a/arch/arm/mach-imx/iomux-v3.c b/arch/arm/mach-imx/iomux-v3.c
index 680d260..c21d8a2 100644
--- a/arch/arm/mach-imx/iomux-v3.c
+++ b/arch/arm/mach-imx/iomux-v3.c
@@ -45,6 +45,8 @@ int mxc_iomux_v3_setup_pad(iomux_v3_cfg_t pad)
        if (!(pad_ctrl & NO_PAD_CTRL) && pad_ctrl_ofs)
                __raw_writel(pad_ctrl, base + pad_ctrl_ofs);
+       else if ((pad_ctrl & NO_PAD_CTRL) && pad_ctrl_ofs)
+               __raw_writel(0, base + pad_ctrl_ofs);
        return 0;


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