On Tue, Feb 12, 2019 at 11:57:55PM +0000, Alex_Gagniuc@xxxxxxxxxxxx wrote: > The recommendation is to set the "in-band PD disable" bit, and it's > possible that platform firmware may have set it at boot time Ok, then I'd suggest to check in pcie_init() whether the feature is supported and enable it if so. And store that fact in a flag, either in struct pci_dev or struct controller. > (*) A bit hypothetical: There is no hardware yet implementing the ECN. Hm, this contradicts Austin Bolen's e-mail of Jan 25 that "Yes, this platform disables in-band presence" (when asked whether your host controller already adheres to the ECN). > I'm > not sure that there is a spec-justifiable reason to not access a device > whose DLL is up, but PD isn't. Austin asked in an e-mail of Jan 24 whether "the hot-inserted device's config space [is] accessed immediately after waiting this 20 + 100 ms delay", which sounded to me like you'd prefer the device not to be accessed until PDS is 1. This can be achieved by polling PDS in pcie_wait_for_link() if in-band presence is disabled, which is why I suggested it. > > Be mindful however that pcie_wait_for_link() is also called from the > > DPC driver. Keith should be able to judge whether a change to that > > function breaks DPC. > > That's why I went for ammending pciehp_handle_presence_or_link_change(). > Smaller bug surface ;). What I'm thinking at this point is, keep the > patch as is, but, also check for in-band PD disable before aborting the > shutdown. Old behavior stays the same. I'm worried that amending pciehp_handle_presence_or_link_change() makes the event handling logic more difficult to understand. Polling PDS in pcie_wait_for_link() or disabling either PDC or DLLSC if in-band presence is disabled seems simpler to reason about. > in-band PD disable (what's a good acronym for that, BTW?) I don't know, maybe inband_presence_disabled? Thanks, Lukas
