Re: [PATCHv2 03/20] PCI: Add required waits on link active

[Keith Busch <keith.busch@intel.com>]

On Thu, Sep 06, 2018 at 01:42:15PM +0200, Lukas Wunner wrote:
> On Wed, Sep 05, 2018 at 02:35:29PM -0600, Keith Busch wrote:
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -4485,21 +4485,33 @@ bool pcie_wait_for_link(struct pci_dev *pdev, bool active)
> >  	bool ret;
> >  	u16 lnk_status;
> >  
> > +	/*
> > +	 * PCIe 4.0r1 6.6.1, a component must enter LTSSM Detect within 20ms,
> > +	 * after which we should expect an link active if the reset was
> > +	 * successful. If so, software must wait a minimum 100ms before sending
> > +	 * configuration requests to devices downstream this port.
> > +	 *
> > +	 * If the link fails to activate, either the device was physically
> > +	 * removed or the link is permanently failed.
> > +	 */
> > +	if (active)
> > +		msleep(20);
> 
> This function is also called by pciehp when bringing up the slot,
> yet I assume the above delay only applies to a Fundamental Reset,
> not hotplug?

Should be any conventional reset, which includes the "cold reset" applying
power to a hot add component.
 
> > +	if (active && ret)
> > +		msleep(100);
> 
> This delay is already observed by pciehp_check_link_status()
> after calling pcie_wait_link_active().

Yeah, that's gone in patch 13. This series became larger than I
originally expected, and there might be a more logical shuffling.