Uwe Kleine-König [off-list ref] writes:

The driver core ignores the return value of struct bus_type::remove()
because there is only little that can be done. To simplify the quest to
make this function return void, let struct vio_driver::remove() return
void, too. All users already unconditionally return 0, this commit makes
it obvious that returning an error code is a bad idea and makes it
obvious for future driver authors that returning an error code isn't
intended.

Note there are two nominally different implementations for a vio bus:
one in arch/sparc/kernel/vio.c and the other in
arch/powerpc/platforms/pseries/vio.c. I didn't care to check which
driver is using which of these busses (or if even some of them can be
used with both) and simply adapt all drivers and the two bus codes in
one go.

I'm 99% sure there's no connection between the two implementations,
other than the name.

So splitting the patch by arch would make it easier to merge. I'm
reluctant to merge changes to sparc code.

The list of powerpc specific drivers is:

  drivers/char/hw_random/pseries-rng.c
  drivers/char/tpm/tpm_ibmvtpm.c
  drivers/crypto/nx/nx-842-pseries.c
  drivers/crypto/nx/nx.c
  drivers/misc/ibmvmc.c
  drivers/net/ethernet/ibm/ibmveth.c
  drivers/net/ethernet/ibm/ibmvnic.c
  drivers/scsi/ibmvscsi/ibmvfc.c
  drivers/scsi/ibmvscsi/ibmvscsi.c
  drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
  drivers/tty/hvc/hvcs.c

cheers