accesses after the BIOS bus scan. The previous revision made the assumption,
that every PCI motherboard did ...
Change the test on the initial value of the CONF1_ADDR_PORT register in a way
that makes the probe succeed on triton based motherboards, without breaking
the EISA motherboard that has some non-PCI register at the same address.
Require the state of the configuration enable bits to be OFF assuming
that the BIOS left them that way, as it should anyway to avoid bad things
to happen.
The tests themselves are copied from the previous release, with the
exception of CONF1_ENABLE_MSK1 having the LSB set. This bit should be
read back as '0', since only DWORD addresses are legal.
Changes relative to 1.12:
- Put extra instruction between outl()/inl() sequence to prevent the
old value being read back because of the bus capacitance.
- Additional check for existence of register at CONF2_ENABLE_PORT.
there is a PCI bus at all) ...
- Do not expect the chip sets to follow even very clearly expressed
requirements of the PCI 2.0 spec.
- Do not read back the value just written to an I/O port without making
sure that some other data have crossed the bus in between ...
fail on new hardware (Compaq Prolinea and Compaq Prosignea), and that
doesn't erroneously identify old mech. 2 chip sets as using mech. 1.
(See section 3.6.4.1.1 of the PCI bus specs rev. 2.0)
