[Skiboot] [PATCH] hw/phb4: Squash the IO bridge window

[Stewart Smith]

"Oliver O'Halloran" <oohall at gmail.com> writes:
> The PCI-PCI bridge spec says that bridges that implement an IO window
> should hardcode the IO base and limit registers to zero.
> Unfortunately, these registers only define the upper bits of the IO
> window and the low bits are assumed to be 0 for the base and 1 for the
> limit address. As a result, setting both to zero can be mis-interpreted
> as a 4K IO window.
>
> This patch fixes the problem the same way PHB3 does. It sets the IO base
> and limit values to 0xf000 and 0x1000 respectively which most software
> interprets as a disabled window.
>
> lspci before patch:
>
> 0000:00:00.0 PCI bridge: IBM Device 04c1 (prog-if 00 [Normal decode])
> 	I/O behind bridge: 00000000-00000fff
>
> lspci after patch:
>
> 0000:00:00.0 PCI bridge: IBM Device 04c1 (prog-if 00 [Normal decode])
> 	I/O behind bridge: None
>
> Signed-off-by: Oliver O'Halloran <oohall at gmail.com>
> ---
>  hw/phb4.c | 8 ++++++++
>  1 file changed, 8 insertions(+)


Merged to master as of b507209d22669ab0a2ad49822d11b2cbb08c49f1

-- 
Stewart Smith
OPAL Architect, IBM.