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

[Balbir Singh]

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
>

Thanks for the review!
Balbir Singh.
>> +             }
>> +     }
>> +     return OPAL_SUCCESS;
>> +}
>> +
>>  static struct pci_slot *npu2_slot_create(struct phb *phb)
>>  {
>>       struct pci_slot *slot;
>> @@ -1191,7 +1210,7 @@ static struct pci_slot *npu2_slot_create(struct phb *phb)
>>       slot->ops.poll_link           = NULL;
>>       slot->ops.hreset              = npu2_hreset;
>>       slot->ops.freset              = npu2_freset;
>> -     slot->ops.creset              = NULL;
>> +     slot->ops.creset              = npu2_creset;
>>
>>       return slot;
>>  }
>> diff --git a/include/npu2.h b/include/npu2.h
>> index dae152a6..c1f39616 100644
>> --- a/include/npu2.h
>> +++ b/include/npu2.h
>> @@ -162,5 +162,6 @@ int64_t npu2_dev_procedure(void *dev, struct pci_cfg_reg_filter *pcrf,
>>  void npu2_dev_procedure_reset(struct npu2_dev *dev);
>>  void npu2_set_link_flag(struct npu2_dev *ndev, uint8_t flag);
>>  void npu2_clear_link_flag(struct npu2_dev *ndev, uint8_t flag);
>> +uint32_t reset_ntl(struct npu2_dev *ndev);
>>  extern int nv_zcal_nominal;
>>  #endif /* __NPU2_H */
>>
>
>