On 09/09/2010 05:24 PM, Cyril Chemparathy wrote: > Hi Mike, > > [...] >> An EMAC soft-reset clobbering the MDIO controller state is a >> possibility. I will poll TI designers to see if this could be the case. > > To test this theory out, I hacked up a crude > beat-it-to-death-and-see-if-it-breaks kinda patch (attached). This > tests 10000 mdio read cycles while constantly doing an emac soft-reset. > > I ran this on a dm365 evm, and the test didn't raise a single failed read: >> davinci_mdio davinci_mdio.0: davinci mdio revision 1.4 >> davinci_mdio davinci_mdio.0: detected phy mask fffffffc >> 10000 test loops completed, 10000 reads ok > > The failure in question seems to be limited to the da8xx family (tested > da830 evm), where: >> davinci_mdio davinci_mdio.0: davinci mdio revision 1.5 >> davinci_mdio davinci_mdio.0: detected phy mask fffffff1 >> idle triggered!! > > The MDIO module upgrade (rev 1.4 -> 1.5) could have something to do with > this behavior. Even so, I can't explain why this issue wasn't seen on > da8xx prior to this series. The original code should (at least in > theory) have sporadically locked up on emac open. > I think, if I understand it correctly, that in the previous version of this code, the emac was reset *prior* to enabling, scanning, and assigning the associated phy on the MDIO bus. The new implementation sets up and scans the MDIO bus first, then comes back around to the EMAC second... hits a reset, and doesn't re-ENABLE the MDIO. Also, maybe hitting the EMAC reset while the MDIO state machine is up is *bad*, I seem to recall some text in the user's guide about waiting for the state machine to stop before disabling it. I wonder if that also applies to reset? -Mike -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
