colibri-pxa320/AX88796: phy-read/write problems
Marc Kleine-Budde
mkl at pengutronix.de
Thu Sep 16 08:09:01 EDT 2010
Hello,
my hardware is a toradex colibri PXA320 board using latest stable
Kernel 2.6.35.4. The Ethernet controller is a AX88796BI.
Ethernet is working, but access via MDIO to the AX's internal phy is
broken. The contents of all registers is 0xffff.
The userspace tool "mii-diag" illustrates the problem:
root at grabowski:~ mii-diag
Using the default interface 'eth0'.
Basic registers of MII PHY #16: ffff ffff ffff ffff ffff ffff ffff ffff.
No MII transceiver present!.
Use '--force' to view the information anyway.
If I switch on the phy_debug in the ax88796 driver we see that the
0xffff are read via "ax_phy_read()" from the hardware, this means it's
not a problem in the userspace.
This is the debug output from the phy register accesses of the generic
mii code, which is polling the link status every 2 seconds.
[ 20.946342] ax_phy_issueaddr: dev c77ec000, 0010, 0001, 2
[ 20.946416] ax_phy_read: 0010.0001 => read ffff
[ 20.946429] ax_phy_issueaddr: dev c77ec000, 0010, 0001, 2
[ 20.946502] ax_phy_read: 0010.0001 => read ffff
[ 22.946336] ax_phy_issueaddr: dev c77ec000, 0010, 0001, 2
[ 22.946410] ax_phy_read: 0010.0001 => read ffff
[ 22.946423] ax_phy_issueaddr: dev c77ec000, 0010, 0001, 2
[ 22.946496] ax_phy_read: 0010.0001 => read ffff
Is this a known problem? It occurs with several colibri boards. Can
someone with a colibri board or a different board with the ax88796 chip
try to reproduce the problem.
cheers, Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Industrial Linux Solutions | Phone: +49-231-2826-924 |
Vertretung West/Dortmund | Fax: +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
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