Re: [PATCH 2/5] PCI: handle FLR failure and allow other reset types

Sinan Kaya
2017-10-12T16:42:16Z

On 10/11/2017 5:00 PM, Bjorn Helgaas wrote:
> On Sat, Sep 23, 2017 at 08:16:55PM -0400, Sinan Kaya wrote:
>> pci_flr_wait() and pci_af_flr() functions assume graceful return even
>> though the device is inaccessible under error conditions.
>>
>> Return -ENOTTY in error cases so that __pci_reset_function_locked() can
>> try other reset types if AF_FLR/FLR reset fails.
>
> This makes sense to me, but I think the error handling in
> __pci_reset_function_locked() is confusing. It currently is:
>
> rc = pci_dev_specific_reset(dev, 0);
> if (rc != -ENOTTY)
> return rc;
> if (pcie_has_flr(dev)) {
> pcie_flr(dev);
> return 0;
> }
> rc = pci_af_flr(dev, 0);
> if (rc != -ENOTTY)
> return rc;
>
> Would it make sense to change this to the following?
>
> rc = pci_dev_specific_reset(dev, 0);
> if (rc == 0)
> return 0;
>
> if (pcie_has_flr(dev)) {
> pcie_flr(dev);
> return 0;
> }
>
> rc = pci_af_flr(dev, 0);
> if (rc == 0)
> return 0;
>

Yeah, this is cleaner. I'll create a separate patch for that.

> I found two cases where this would make a difference: reset_ivb_igd()
> returns -ENOMEM if pci_iomap() fails, and pci_pm_reset() returns
> -EINVAL if the device is not in D0.
>
> In both cases we currently return the failure, but it would seem
> reasonable to me to try another reset method.
>
> That could be done in a new patch before this one. Then *this* patch
> could use -ETIMEDOUT instead of -ENOTTY, and I think the whole thing
> would become a little more readable.
>
>> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
>> ---

--
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.