[Skiboot] [PATCH v3 3/5] hw/phb3: disable CAPI mode during complete reset

[Andrew Donnellan]

On 27/01/17 18:33, Andrew Donnellan wrote:
> When fast rebooting or kexec-ing a system with a PHB in CAPI mode, we need
> to return the PHB to regular PCIe mode.
>
> In order to do this, we have to reset a bunch of registers to their
> pre-CAPI-mode state. However, doing this while there is traffic going over
> the PCI link is dangerous and will generally cause a checkstop.
>
> As such, we want to do this while the PHB is fenced. Conveniently, during a
> complete reset we force a PHB fence, so this is a good opportunity to
> disable CAPI mode.
>
> When doing a complete reset, if the PHB is in CAPI mode, execute a sequence
> of SCOMs to reset PHB-related registers back to their regular, PCIe mode
> values.
>
> Signed-off-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>

So I'm currently looking into one of our test machines (for the IBM CAPI 
people: freak) where we reliably panic on kexec due to a stack of fatal 
nonrecoverable HMIs, though fast reboot works fine. I haven't been able 
reproduce this so far on any of the other machines I've tested on.

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan at au1.ibm.com  IBM Australia Limited