Re: [PATCH 1/2] PCI: save and restore device state during bus reset

From: Sinan Kaya
Date: Tue Sep 13 2016 - 19:31:32 EST

On 9/13/2016 7:20 PM, Sinan Kaya wrote:
> On 9/13/2016 5:53 PM, Bjorn Helgaas wrote:
>>> + pci_bus_restore(dev->bus);
>> This path eventually writes the Bridge Control register:
>> pci_reset_bridge_secondary_bus
>> pcibios_reset_secondary_bus
>> pci_reset_secondary_bus
>> pci_write_config_word(dev, PCI_BRIDGE_CONTROL, ctrl)
>> But I think it'd be easy to call this on a non-bridge device, and I
>> don't think there's anything in the path that checks whether this is
>> actually a bridge. I wonder if we should check that somewhere, or
>> maybe even change the interface so it takes a struct pci_bus instead
>> of a pci_dev.
> I'll change it to pci_bus.
>>>> +}

Changing the API seems to become a bigger mess. pcibios_reset_secondary_bus has
weaker friends in different architectures.

I can move the check in pci_parent_bus_reset

if (pci_is_root_bus(dev->bus) || dev->subordinate ||
!dev->bus->self || dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET)
return -ENOTTY;

inside pci_reset_bridge_secondary_bus instead.

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.