Re: [Xen-devel] [PATCH V3 1/2] Drivers/PCI: Export pcie_has_flr() interface

Govinda Tatti
2017-12-13T20:48:16Z

>>>> -static bool pcie_has_flr(struct pci_dev *dev)
>>>> +bool pcie_has_flr(struct pci_dev *dev)
>>>> {
>>>> u32 cap;
>>>> @@ -3882,6 +3882,7 @@ static bool pcie_has_flr(struct pci_dev *dev)
>>>> pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &cap);
>>>> return cap & PCI_EXP_DEVCAP_FLR;
>>>> }
>>>> +EXPORT_SYMBOL_GPL(pcie_has_flr);
>>> I'd rather change pcie_flr() so you could *always* call it, and it
>>> would return 0, -ENOTTY, or whatever, based on whether FLR is
>>> supported. Is that feasible?
>> Sure, I will add pcie_has_flr() logic inside pcie_flr() and return
>> appropriate
>> values as suggested by you. Do we still want to retain pcie_has_flr() and
>> its usage inside pci.c?.Otherwise, I will remove it and do required cleanup.
> If you can restructure the code and remove pcie_has_flr() while
> retaining the existing behavior of its callers, that would be great.
I checked the current usage of pcie_has_flr() and pcie_flr(). I have a
couple
of questions or need some clarification.

1. pcie_has_flr() usage inside pci_probe_reset_function().

This function is only calling pcie_has_flr() but not pcie_flr().
Rest of the code is trying to do specific type of reset except
pcie_flr().

rc = pci_dev_specific_reset(dev, 1);
if (rc != -ENOTTY)
return rc;
if (pcie_has_flr(dev))
return 0;
rc = pci_af_flr(dev, 1);
if (rc != -ENOTTY)
return rc;

In other-words, I can remove usage of pcie_has_flr() in all other places
in pci.c except in above function.

2. W.r.t pcie_flr(), I am planning to return error code. Currently, the
following
file/modules are calling this function. My plan is to add a check
for return
code and print a WANRING message if return code is NON-ZERO. I hope
this is
sufficient for this patch.

drivers/crypto/qat/qat_common/adf_aer.c
drivers/infiniband/hw/hfi1/chip.c (2 places)
drivers/net/ethernet/cavium/liquidio/lio_vf_main.c
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c (2 places)
drivers/pci/quirks.c (2 places)

Cheers
GOVINDA