[Skiboot] [PATCH] hw/npu2: support creset of npu2 devices

[Balbir Singh]

On Sun, Dec 17, 2017 at 3:56 PM, Balbir Singh <bsingharora at gmail.com> wrote:
> On Fri, Dec 15, 2017 at 2:38 PM, Alistair Popple <alistair at popple.id.au> wrote:
>> On Friday, 15 December 2017 1:59:42 PM AEDT Balbir Singh wrote:
>>> creset calls in the hw procedure that resets the PHY, we don't
>>> take them out of reset, just put them in reset.
>>>
>>> Signed-off-by: Balbir Singh <bsingharora at gmail.com>
>>> ---
>>>  hw/npu2-hw-procedures.c |  2 +-
>>>  hw/npu2.c               | 21 ++++++++++++++++++++-
>>>  include/npu2.h          |  1 +
>>>  3 files changed, 22 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/hw/npu2-hw-procedures.c b/hw/npu2-hw-procedures.c
>>> index 1318e867..dfff4a2a 100644
>>> --- a/hw/npu2-hw-procedures.c
>>> +++ b/hw/npu2-hw-procedures.c
>>> @@ -233,7 +233,7 @@ static bool poll_fence_status(struct npu2_dev *ndev, uint64_t val)
>>>  }
>>>
>>>  /* Procedure 1.2.1 - Reset NPU/NDL */
>>> -static uint32_t reset_ntl(struct npu2_dev *ndev)
>>> +uint32_t reset_ntl(struct npu2_dev *ndev)
>>>  {
>>>       uint64_t val;
>>>
>>> diff --git a/hw/npu2.c b/hw/npu2.c
>>> index 7ffb0941..ee75b6fd 100644
>>> --- a/hw/npu2.c
>>> +++ b/hw/npu2.c
>>> @@ -1170,6 +1170,25 @@ static int64_t npu2_freset(struct pci_slot *slot __unused)
>>>       return OPAL_SUCCESS;
>>>  }
>>>
>>> +static int64_t npu2_creset(struct pci_slot *slot)
>>> +{
>>> +     struct npu2 *p;
>>> +     int i;
>>> +     struct npu2_dev *ndev;
>>> +
>>> +     p = phb_to_npu2(slot->phb);
>>> +     NPU2INF(p, "Creset PHB state\n");
>>> +
>>> +     for (i = 0; i < p->total_devices; i++) {
>>
>> Wont this reset every link on the NPU rather than just the given pci_slot? We
>> need to make sure this resets just the specified device.
>
> We have a slot for each of the struct npu2 and total_devices are the
> total number of devices on that phb. In the tests on a 4 GPU system, I
> did not find anything missing or extra. I'll double check
>
>>
>>> +             ndev = &p->devices[i];
>>> +             if (ndev) {
>>> +                     NPU2DEVINF(ndev, "Resetting device\n");
>>> +                     reset_ntl(ndev);
>>
>> What is the motivation for implementing this? I suspect we should also reset the
>> DL and PHY.
>>
>
> A creset should set the links to reset state, I'm just following the
> procedure I am aware of. I do not want to bring these links out of
> reset
>
>
>> Regards,
>>
>> Alistair

We discussed this offline as well, did you want to see any more changes?

Balbir