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

Michael Ellerman mpe at ellerman.id.au
Fri Dec 8 23:03:06 AEDT 2017


"Guilherme G. Piccoli" <gpiccoli at linux.vnet.ibm.com> writes:

> On 11/21/2017 12:35 AM, Balbir Singh wrote:
>> 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
>
> It was, in v1. But mpe asked it to be a powerpc specific parameter heheh

LOL. Turtles.

I still feel like we shouldn't be creating a generically named parameter
like this, though we have done it many times in the past.

Can we call it "ppc_reset_phbs". And then I'll merge it without further
quibbling, honest.

cheers


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