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

["Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com>]

On 11/21/2017 12:35 AM, Balbir Singh wrote:
> On Thu, Nov 16, 2017 at 11:14 PM, Guilherme G. Piccoli
> <gpiccoli@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@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
Cheers,


Guilherme

> 
> Balbir
>