Re: [PATCH v6 4/4] PCI: designware: Add iATU Unroll feature

[Fabio Estevam]

Hi Tim,

On Tue, Nov 15, 2016 at 10:22 PM, Tim Harvey <tharvey@xxxxxxxxxxxxx> wrote:

> Bjorn / Joao,
>
> This patch (from commit a0601a47053714eecec726aea5ebcd829f817497) is
> causing a kernel regression in 4.9. I can no longer boot the kernel on
> boards that have a PCIe switch downstream from the IMX6 (ie many of
> the Gateworks Ventana boards) unless PCI is enabled in the bootloader
> (which is not recommended as that causes PCI link in the kernel to
> occasionally fail).

This has been fixed in 4.9-rc4 by the following commit:

commit 416379f9ebded501eda882e6af0a7aafc1866700
Author: Niklas Cassel <niklas.cassel@xxxxxxxx>
Date:   Fri Oct 14 23:54:55 2016 +0200

    PCI: designware: Check for iATU unroll support after initializing host

    dw_pcie_iatu_unroll_enabled() reads a dbi_base register.  Reading any
    dbi_base register before pp->ops->host_init has been called causes
    "imprecise external abort" on platforms like ARTPEC-6, where the PCIe
    module is disabled at boot and first enabled in pp->ops->host_init.  Move
    dw_pcie_iatu_unroll_enabled() to dw_pcie_setup_rc(), since it is after
    pp->ops->host_init, but before pp->iatu_unroll_enabled is actually used.

    Fixes: a0601a470537 ("PCI: designware: Add iATU Unroll feature")
    Tested-by: James Le Cuirot <chewi@xxxxxxxxxx>
    Signed-off-by: Niklas Cassel <niklas.cassel@xxxxxxxx>
    Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
    Acked-by: Joao Pinto <jpinto@xxxxxxxxxxxx>
    Acked-by: Olof Johansson <olof@xxxxxxxxx>