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

poza
2018-06-11T10:01:51Z

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.

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

Regards,
Oza.