[PATCH 0/3] pci: fix/cleanup pcix get and set mmrbc functions

[Dean Nelson <dnelson@redhat.com>]

A customer running RHEL4.8 encountered

 "e1000: eth0: e1000_clean_tx_irq: Detected Tx Unit Hang"

type errors, which were determined to be the result of a bad return value
from e1000_pcix_get_mmrbc() causing the call to e1000_pcix_set_mmrbc() to
be skipped in the following snippet of code from e1000_init_hw().

	switch (hw->mac_type) {
	case e1000_82545_rev_3:
	case e1000_82546_rev_3:
		break;
	default:
		/* Workaround for PCI-X problem when BIOS sets MMRBC incorrectly. */
		if (hw->bus_type == e1000_bus_type_pcix
		    && e1000_pcix_get_mmrbc(hw) > 2048)
			e1000_pcix_set_mmrbc(hw, 2048);
		break;
	}

e1000_pcix_get_mmrbc() is basically a wrapper for a call to pcix_get_mmrbc().
e1000_pcix_set_mmrbc() is the same for pcix_set_mmrbc().

The following three patches are a response to the problems that were found to
exist with pcix_get_max_mmrbc(), pcix_get_mmrbc() and pcix_set_mmrbc().

Versions of these patches applicable to RHEL4 were verified by the customer to
solve their problem.