linux-kernel - Re: [PATCH option B 2/2] PCI: do not create quirk I/O regions below PCIBIOS_MIN

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Date:	Fri, 11 Feb 2011 15:09:40 +0300
From:	Sergei Shtylyov <sshtylyov@...sta.com>
To:	Jiri Slaby <jslaby@...e.cz>
CC:	jbarnes@...tuousgeek.org, linux-pci@...r.kernel.org,
	linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org,
	jirislaby@...il.com, Bjorn Helgaas <bjorn.helgaas@...com>,
	"David S. Miller" <davem@...emloft.net>,
	Thomas Renninger <trenn@...e.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH option B 2/2] PCI: do not create quirk I/O regions below
 PCIBIOS_MIN_IO for ICH

Hello.

On 14-01-2011 13:32, Jiri Slaby wrote:

> Some broken BIOSes on ICH4 chipset report an ACPI region which is in
> conflict with legacy IDE ports when ACPI is disabled. Even though the
> regions overlap, IDE ports are working correctly (we cannot find out
> the decoding rules on chipsets).
>
> So the only problem is the reported region itself, if we don't reserve
> the region in the quirk everything works as expected.

> This patch avoids reserving any quirk regions below PCIBIOS_MIN_IO
> which is 0x1000. Some regions might be (and are by a fast google
> query) below this border, but the only difference is that they won't
> be reserved anymore. They should still work though the same as before.

> The conflicts look like (1f.0 is bridge, 1f.1 is IDE ctrl):
> pci 0000:00:1f.1: address space collision: [io 0x0170-0x0177] conflicts with 0000:00:1f.0 [io  0x0100-0x017f]

> At 0x0100 a 128 bytes long ACPI region is reported in the quirk for
> ICH4. ata_piix then fails to find disks because the IDE legacy ports
> are zeroed:
> ata_piix 0000:00:1f.1: device not available (can't reserve [io 0x0000-0x0007])

> References: https://bugzilla.novell.com/show_bug.cgi?id=558740
> Signed-off-by: Jiri Slaby <jslaby@...e.cz>
> Cc: Bjorn Helgaas <bjorn.helgaas@...com>
> Cc: Jesse Barnes <jbarnes@...tuousgeek.org>
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: Thomas Renninger <trenn@...e.de>
> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
[...]

> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 8db2426..b3ab2f7 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -554,18 +554,30 @@ static void __devinit quirk_ich4_lpc_acpi(struct pci_dev *dev)
>   	u32 region;
>   	u8 enable;
>
> +	/*
> +	 * The check for PCIBIOS_MIN_IO is to ensure we won't create a conflict
> +	 * with low legacy (and fixed) ports. We don't know the decoding
> +	 * priority and can't tell whether the legacy device or the one created
> +	 * here is really at that address.  This happens on boards with broken
> +	 * BIOSes.
> +	*/
> +
>   	pci_read_config_byte(dev, ICH_ACPI_CNTL,&enable);
>   	if (enable&  ICH4_ACPI_EN) {
>   		pci_read_config_dword(dev, ICH_PMBASE,&region);
> -		quirk_io_region(dev, region, 128, PCI_BRIDGE_RESOURCES,
> -				"ICH4 ACPI/GPIO/TCO");
> +		region &= PCI_BASE_ADDRESS_IO_MASK;

    Why don't you do the masking right in the patch #1? And is it really 
necessary if the region size is known to be 128 bytes?

WBR, Sergei
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