[PATCH v2] powerpc/powernv: Add pci_reset_phbs parameter to issue a PHB reset

Balbir Singh bsingharora at gmail.com
Tue Nov 21 13:35:31 AEDT 2017

On Thu, Nov 16, 2017 at 11:14 PM, Guilherme G. Piccoli
<gpiccoli at linux.vnet.ibm.com> wrote:
> On 11/16/2017 01:49 AM, Balbir Singh wrote:
>> On Thu, Oct 26, 2017 at 2:27 AM, Guilherme G. Piccoli
>> <gpiccoli at linux.vnet.ibm.com> wrote:
>>> During a kdump kernel boot in PowerPC, we request a reset of the PHBs
>>> to the FW. It makes sense, since if we are booting a kdump kernel it
>>> means we had some trouble before and we cannot rely in the adapters'
>>> health; they could be in a bad state, hence the reset is needed.
>>> But this reset is useful not only in kdump - there are situations,
>>> specially when debugging drivers, that we could break an adapter in
>>> a way it requires such reset. One can tell to just go ahead and
>>> reboot the machine, but happens that many times doing kexec is much
>>> faster, and so preferable than a full power cycle.
>>> This patch adds the pci_reset_phbs parameter to perform such reset
>>> when desired by the user.
>> Do we care to reset specific phbs or all of them? I guess all based on
>> your description.
> Exactly Balbir, it does reset all of them. We could add such
> granularity, but I don't see much usability..
> But if somebody feels it's useful, we can change...

OK.. makes sense, any reason why this can't be folded into reset_devices?
I guess we want reset_phbs to be independent of reset_devices


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