linux-kernel - Re: [PATCH 3/3] Add NumaChip quirk

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Date:	Tue, 25 Oct 2011 08:38:10 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Daniel J Blueman <daniel@...ascale-asia.com>
Cc:	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	H Peter Anvin <hpa@...or.com>,
	Steffen Persvold <sp@...ascale.com>,
	linux-kernel@...r.kernel.org, x86@...nel.org,
	Jesse Barnes <jbarnes@...tuousgeek.org>
Subject: Re: [PATCH 3/3] Add NumaChip quirk

On Tue, Oct 18, 2011 at 2:22 AM, Daniel J Blueman
<daniel@...ascale-asia.com> wrote:
> Add quirk for Numascale's NumaChip to prevent resource conflicts.
>
> v2:
>  - [Daniel] rediffed and validated against 3.1-rc10
>
> Signed-off-by: Steffen Persvold <sp@...ascale.com>
> Signed-off-by: Daniel J Blueman <daniel@...ascale-asia.com>
> ---
>  drivers/pci/quirks.c    |   14 ++++++++++++++
>  include/linux/pci_ids.h |    4 ++++
>  2 files changed, 18 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 1196f61..051b793 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -2679,6 +2679,20 @@ static void __devinit quirk_hotplug_bridge(struct pci_dev *dev)
>
>  DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_HINT, 0x0020, quirk_hotplug_bridge);
>
> +/* Clear all resources on NumaChip to avoid conflicts */
> +static void __devinit numachip_resource_fixup(struct pci_dev *pdev)
> +{
> +       int i;
> +
> +       for (i = PCI_STD_RESOURCES; i <= PCI_ROM_RESOURCE; i++)
> +               memset(&pdev->resource[i], 0, sizeof(pdev->resource[i]));
> +
> +       dev_notice(&pdev->dev, "Disabled all PCI resources for NumaChip\n");
> +}
> +
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_NUMASCALE,
> +       PCI_DEVICE_ID_NUMASCALE_NUMACHIP0, numachip_resource_fixup);

This feels like a band-aid ... what's the background here?  I can see
that you're disabling PCI resources, and I can read that this avoids
conflicts, but what's the underlying cause of the conflict?

I wonder if there's a more generic problem that should be fixed
differently.  Presumably the NumaChip designers put those BARs there
for a reason, and often when we report "conflicts," it's really a clue
that we're doing something wrong in host bridge discovery or in
generic PCI.

Can you post a complete dmesg log showing the conflict?

Bjorn
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