Hi, Sorry for replying directly from gmail, I don't have the Linux environment ready yet :) Niklas patch is the one that should be applied, because in the host_init we need to know if the iATU is in Unroll or in Legacy mode. Thanks. 2016-10-21 17:22 GMT+01:00 Bjorn Helgaas <helgaas@xxxxxxxxxx>: > [+cc Joao, Niklas, Carlos, Jose, Jesper] > > On Fri, Oct 21, 2016 at 10:31:42AM -0500, Bjorn Helgaas wrote: >> On Tue, Oct 18, 2016 at 10:25:49AM +0200, Lucas Stach wrote: >> > The function used to determine if iATU unroll is available will read >> > a RC register. This is not possible and will result in a system hang >> > if the RC is still in reset, so it is only safe to call this function >> > after host_init() has been called. >> >> I'm sure Joao tested a0601a470537 somewhere, so I assume this hang only >> happens on certain systems? >> >> I'm wondering if this is suggesting something that's currently done >> differently across the drivers but could be done more similarly. >> >> > Fixes: a0601a470537 (PCI: designware: Add iATU Unroll feature) >> > Reported-by: Gary Bisson <gary.bisson@xxxxxxxxxxxxxxxxxxx> >> > Tested-by: Gary Bisson <gary.bisson@xxxxxxxxxxxxxxxxxxx> >> > Signed-off-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx> >> > --- >> > drivers/pci/host/pcie-designware.c | 4 ++-- >> > 1 file changed, 2 insertions(+), 2 deletions(-) >> > >> > diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-designware.c >> > index 035f50c03281..74510508fafc 100644 >> > --- a/drivers/pci/host/pcie-designware.c >> > +++ b/drivers/pci/host/pcie-designware.c >> > @@ -637,11 +637,11 @@ int dw_pcie_host_init(struct pcie_port *pp) >> > } >> > } >> > >> > - pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled(pp); >> > - >> > if (pp->ops->host_init) >> > pp->ops->host_init(pp); >> > >> > + pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled(pp); >> > + > > Niklas suggested this exact change earlier [1], but Joao pointed out the > problem with calling dw_pcie_iatu_unroll_enabled() after calling > pp->ops->host_init(): > > dw_pcie_host_init > pp->ops->host_init > dw_pcie_setup_rc > dw_pcie_prog_outbound_atu > if (pp->iatu_unroll_enabled) > ... > pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled() > > We check iatu_unroll_enabled in dw_pcie_prog_outbound_atu() before it > has been set. > > Niklas' second patch [2] looks like a better fix. Can you guys take a > look and see if you agree? > > [1] http://lkml.kernel.org/r/b53d5807-8199-5789-6184-e37324a1d79e@xxxxxxxx > [2] http://lkml.kernel.org/r/1476482095-26289-1-git-send-email-niklass@xxxxxxxx > >> > pp->root_bus_nr = pp->busn->start; >> > if (IS_ENABLED(CONFIG_PCI_MSI)) { >> > bus = pci_scan_root_bus_msi(pp->dev, pp->root_bus_nr, >> > -- >> > 2.9.3 >> > >> > -- >> > 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 >> -- >> 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 -- 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
