On Tue, Nov 28, 2017 at 08:03:05PM -0800, Paul B. Henson wrote: > The EHCI ports seem to work fine under Linux, including the LTE modem > when attached to them, so this seems to be an issue with openbsd, not > faulty hardware per se. The Linux driver does have a couple of > workarounds in their EHCI driver for AMD chipsets, I'm not sure if > either of them are relevant for this; one involves disabling low power > mode during transfers and the other says: > > "EHCI controller on AMD SB700/SB800/Hudson-2/3 platforms may > read/write memory space which does not belong to it when > there is NULL pointer with T-bit set to 1 in the frame list > table. To avoid the issue, the frame list link pointer > should always contain a valid pointer to a inactive qh" > > I don't see anything specifically discussing flaky interrupts. Any > thoughts on what might be going on here with USB and how it fix it? >
Problems with ehci(4) on AMD SB700 are known. For instance, athn(4) USB devices don't work on such ports. Could you try adding missing workarounds to our EHCI driver to fix your problem? That would probably help with other known issues, too.
