Mark Lord wrote:

I'm certain there are lots of vendor-specific commands
that might assume exclusive bus access, if not exclusive
host access.  All of this makes a reasonable case for
having libata stop other host activity before/while
performing any passthru command.

We also have internal commands during error handling (and soon PM) to 
worry about, so its not as simple as that.  It implies a larger good at 
when we can queue commands, and how to synchronize them across multiple 
ports.  We need to do this for Simplex DMA, too.

	Jeff