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

[okaya]

On 2018-06-08 00:57, poza@xxxxxxxxxxxxxx wrote:
> On 2018-06-08 03:04, Bjorn Helgaas wrote:
> > On Thu, Jun 07, 2018 at 07:18:03PM +0530, poza@xxxxxxxxxxxxxx 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@xxxxxxxxxxxxxx>
> > > >
> > > > 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.
>
>
> Yes Bjorn thats right.
> I am trying to understand it but no clue.
> since it is restoring the stuffs in ERR_FATAL case, why would PCIe
> bridge loose all the settings ?  [config space, aer bits, master,
> device enable etc..)
> Max we do is link_reset in ERR_FATAL case, and Secondary bus reset
> should affect downstream components (not upstream)

Our first generation controller had this problem. There could be others 
too.