Re: [Qemu-devel] [PATCH] ohci: Stop OHCI bus when PCI bus master is disabled

[Gerd Hoffmann]

On Do, 2014-09-11 at 17:11 +1000, Alexey Kardashevskiy wrote:
> When the guest performs kexec() (for example, as a part of kdump),
> new kernel does PCI probing. As a part of it, PCI_COMMAND_MASTER
> gets disabled which disables bus master memory region.
> Since ohci_frame_boundary() timer is not stopped at this point
> as OHCI device was not reset, the device tries accessing DMA memory,
> fails and ends up in ohci_die() producing errors:
> 
> usb-ohci: HCCA read error at 30000000
> ohci_die: DMA error

Which is the correct behavior.

IMHO the kernel should stop ohci before doing kexec.

Independant of that we can move the ohci error logging to tracepoints,
so ohci emulation is silent by default.

cheers,
  Gerd