In virtualized environments indirect access to the device may not be supported
(depending on the Hypervisor type). Indirect device access was used since in
some harware contexts (i.e. certain chipset and BIOS) every access the driver
makes across the pci is followed by a BIOS initiated Zero Length Read to the
same address. When accessing widebus registers this zero length read corrupts
the serialization of the read/write sequence resulting with errors. To avoid
this problem widebus registers are always accessed via the DMAE or the indirect
interface. However, the 57712x and 578xx devices intercept the zero length read
and so using the indirect interface with these devices is not necessary. Since
PDA is only supported for 57712x and 578xx the indirect access to device was
restricted to 57710 and 57711x.
Signed-off-by: Ariel Elior <ariele@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>