Re: [PATCH NEXT 6/6] PCI/PORTDRV: Remove ERR_FATAL handling from pcie_portdrv_slot_reset()

poza
2018-06-11T12:50:34Z

On 2018-06-11 15:31, poza@codeaurora.org wrote:
> On 2018-06-08 03:04, Bjorn Helgaas wrote:
>> On Thu, Jun 07, 2018 at 07:18:03PM +0530, poza@codeaurora.org wrote:
>>> On 2018-06-07 11:30, Oza Pawandeep wrote:
>>> > We are handling ERR_FATAL by resetting the Link in software,skipping the
>>> > driver pci_error_handlers callbacks, removing the devices from the PCI
>>> > subsystem, and re-enumerating, as a result of that, no more calling
>>> > pcie_portdrv_slot_reset in ERR_FATAL case.
>>> >
>>> > Signed-off-by: Oza Pawandeep <poza@codeaurora.org>
>>> >
>>> > diff --git a/drivers/pci/pcie/portdrv_pci.c
>>> > b/drivers/pci/pcie/portdrv_pci.c
>>> > index 973f1b8..92f5d330 100644
>>> > --- a/drivers/pci/pcie/portdrv_pci.c
>>> > +++ b/drivers/pci/pcie/portdrv_pci.c
>>> > @@ -42,17 +42,6 @@ __setup("pcie_ports=", pcie_port_setup);
>>> >
>>> > /* global data */
>>> >
>>> > -static int pcie_portdrv_restore_config(struct pci_dev *dev)
>>> > -{
>>> > - int retval;
>>> > -
>>> > - retval = pci_enable_device(dev);
>>> > - if (retval)
>>> > - return retval;
>>> > - pci_set_master(dev);
>>> > - return 0;
>>> > -}
>>> > -
>>> > #ifdef CONFIG_PM
>>> > static int pcie_port_runtime_suspend(struct device *dev)
>>> > {
>>> > @@ -162,14 +151,6 @@ static pci_ers_result_t
>>> > pcie_portdrv_mmio_enabled(struct pci_dev *dev)
>>> >
>>> > static pci_ers_result_t pcie_portdrv_slot_reset(struct pci_dev *dev)
>>> > {
>>> > - /* If fatal, restore cfg space for possible link reset at upstream */
>>> > - if (dev->error_state == pci_channel_io_frozen) {
>>> > - dev->state_saved = true;
>>> > - pci_restore_state(dev);
>>> > - pcie_portdrv_restore_config(dev);
>>> > - pci_enable_pcie_error_reporting(dev);
>>> > - }
>>> > -
>>> > return PCI_ERS_RESULT_RECOVERED;
>>> > }
>>>
>>>
>>> Hi Bjorn,
>>>
>>> the above patch removes ERR_FATAL handling from
>>> pcie_portdrv_slot_reset()
>>> because now we are handling ERR_FATAL differently than before.
>>>
>>> I tried to dig into pcie_portdrv_slot_reset() handling for ERR_FATAL
>>> case
>>> where it
>>> restores the config space, enable device, set master and enable error
>>> reporting....
>>> and as far as I understand this is being done for upstream link
>>> (bridges
>>> etc..)
>>>
>>> why was it done at the first point (I checked the commit description,
>>> but
>>> could not really get it)
>>> and do we need to handle the same thing in ERR_FATAL now ?
>>
>> You mean 4bf3392e0bf5 ("PCI-Express AER implemetation: pcie_portdrv
>> error handler"), which added pcie_portdrv_slot_reset()? I agree, that
>> commit log has no useful information. I don't know any of the history
>> behind it.
>
> Hi Bjorn and Keith,
>
> broadcast_error_message()
> if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
> .....
> pci_walk_bus(dev->subordinate, cb, &result_data);
>
>
> so in case of ERR_FATAL, the walk bus is happening on subordinates,
> and if I understand the walk right
> then, pcie_portdrv_slot_reset() is called only on BRIDGES/Switches
>
> If is never called on Root-Ports
>
> having said that, now since we are removing the devices (compare to
> previous error callback handling in ERR_FATAL)
> I dont see the need of the above code anymore.
>

when I say above code, I meant this patch itself which removes ERR_FATAL
handling out of pcie_portdrv_slot_reset

> because there is nothing to restore to any more. as we are initiating
> re-enumeration.
>
> Regards,
> Oza.