data_xfer too fast? - SATA PIO

["Mat Loikkanen" <Mat.Loikkanen@synopsys.com>]

We've run into the issue of ata_mmio_data_xfer() reading our host
controller's data fifo too fast -- requesting a data word when the fifo was
empty, before the device had sent PIO data (in our observed case somewhere
in the middle of a 512 byte IDENTIFY DEVICE PIO data transfer).  I can't see
any provision in Libata for a case like ours where the processor and bus are
"too fast".  Has anyone run into this issue before?  Any ideas on what we
should do about it?  We can make our host controller to wait-state the bus
... but for how long, what if data never arrives ...  Thanks for any help.

-mat
 
Mat Loikkanen
Synopsys, Inc.