On Mon, 14 Nov 2016 15:03:19 -0600 Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > On Wed, Oct 26, 2016 at 12:01:40PM -0600, Alex Williamson wrote: > > As described in the included code comment, this quirk is intended to > > work around an errata in a variety of Pericom 4-lane, 3 and 4 port > > PCIe 2.0 switches. The switches advertise ACS capabilities, but the > > P2P Request Redirection support includes an errata that PCI_ACS_RR > > effectively doesn't work and results in transactions being queued and > > not delivered within the PCIe switch. The errata has no planned > > hardware fix. > > Is there a published erratum we can reference here? It'd be really > nice to have a URL. Unfortunately only the product briefs seem to be public. I was sent an errata, but it's marked confidential, so I don't think I'll risk adding it to the bz. I haven't even been granted access to the datasheet. I'm only guessing at the affected devices IDs based on my sample of one. One thing I've thought of since I posted this series is that it's possible to have a configuration where the downstream ports don't all match. If the upstream port is running at 5GT/s, the first downstream port is also running 5GT/s, but another downstream port is running 2.5GT/s, this code will retrain the upstream port to 2.5GT/s w/o revisiting that first port. I should fix that, but I likely won't have time for v4.10. If you want to de-queue this, I'll try to look at it again for v4.11 and take your other suggestions into account. Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
