RE: [PATCH 2/2] PCI: fix system hang issue of Marvell SATA hostcontroller

[Xiangliang Yu]

Hi, Bjorn

> > Fix system hang issue: if first accessed resource file of BAR0 ~
> > BAR4, system will hang after executing lspci command
> 
> This needs more explanation.  We've already read the BARs by the time
> header quirks are run, so apparently it's not just the mere act of
> accessing a BAR that causes a hang.
> 
> We need to know exactly what's going on here.  For example, do BARs
> 0-4 exist?  Does the device decode accesses to the regions described
> by the BARs?  The PCI core has to know what resources the device uses,
> so if the device decodes accesses, we can't just throw away the
> start/end information.
The BARs 0-4 is exist and the PCI device is enable IO space, but user access the regions file by udevadm command with info parameter, the system will hang.
Like this: udevadmin info --attribut-walk --path=/sys/device/pci-device/000:*.
Because the device is just AHCI host controller, don't need the BAR0 ~ 4 region file. 
Is my explanation ok for the patch?


> 
> > ---
> >  drivers/pci/quirks.c |   15 +++++++++++++++
> >  1 files changed, 15 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> > index 0369fb6..d49f8dc 100644
> > --- a/drivers/pci/quirks.c
> > +++ b/drivers/pci/quirks.c
> > @@ -44,6 +44,21 @@ static void quirk_mmio_always_on(struct pci_dev *dev)
> >  DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_ANY_ID, PCI_ANY_ID,
> >                                 PCI_CLASS_BRIDGE_HOST, 8,
> quirk_mmio_always_on);
> >
> > +/* The BAR0 ~ BAR4 of Marvell 9125 device can't be accessed
> > +*  by IO resource file, and need to skip the files
> > +*/
> > +static void quirk_marvell_mask_bar(struct pci_dev *dev)
> > +{
> > +       int i;
> > +
> > +       for (i = 0; i < 5; i++)
> > +               if (dev->resource[i].start)
> > +                       dev->resource[i].start =
> > +                               dev->resource[i].end = 0;
> > +}
> > +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_MARVELL_EXT, 0x9125,
> > +                               quirk_marvell_mask_bar);
> > +
> >  /* The Mellanox Tavor device gives false positive parity errors
> >   * Mark this device with a broken_parity_status, to allow
> >   * PCI scanning code to "skip" this now blacklisted device.
> > --
> > 1.7.5.4
> >
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