So this would definitely break CardBus VGA adapters (if the
bridges comply with their spec)... do we mind? I'd rather
just mention it in the commit message.
Patch Set #1, Line 17:
these days, so nobody noticed.
Looks like this bit is only defined when upstream is PCIe and downstream is PCI/PCI-X/AGP(?), given […]
It's often reserved, read zero (including PC Card 8.0). It's in PCI-to-PCI
bridge 1.2 and in PCIe-to-PCI/PCI-X 1.0.
Fun fact: VGA Enable (bit 3) seems to be only mandatory in the PC Card spec
;) so far, we just assume that it's present.
With slots, I guess you mean root ports? Yes, they are covered by the
PCIe base spec. aaaaaaand, they only added the bits in 4.0 xD
Anyway, if we'd have passed more than a decade without legacy VGA,
we'd have noticed.
Patch Set #1, Line 822:
bridge_ctrl = pci_read_config16(bus->dev, PCI_BRIDGE_CONTROL);
Write with CTL_VGA=0,CTL_VGA16=1 is strange/unexpected. […]
Ooff, I assumed the other case, that hardware might mind if we change
VGA16 while VGA is off... I don't think this can be solved without
time travel and tighter specs.
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