linux-kernel - Re: [PATCH] support PCI MCFG space on Intel i915 bridges

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Message-id: <463679A4.60704@shaw.ca>
Date:	Mon, 30 Apr 2007 17:20:04 -0600
From:	Robert Hancock <hancockr@...w.ca>
To:	Jesse Barnes <jesse.barnes@...el.com>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] support PCI MCFG space on Intel i915 bridges

Jesse Barnes wrote:
> On Sunday, April 29, 2007 7:10 pm Robert Hancock wrote:
>> Jesse Barnes wrote:
>>> Add support for Intel 915 bridge chips to the new PCI MMConfig
>>> detection code.  Tested and works on my sole 915 based platform (a
>>> Toshiba laptop).  I added register masking per Oliver's suggestion,
>>> and moved the __init qualifier to after the 'static const char' to
>>> match Ogawa-san's recent cleanup patches.
>>>
>>> Signed-off-by:  Jesse Barnes <jesse.barnes@...el.com>
>>>
>>> diff --git a/arch/i386/pci/mmconfig-shared.c
>>> b/arch/i386/pci/mmconfig-shared.c index 747d8c6..1339d31 100644
>>> --- a/arch/i386/pci/mmconfig-shared.c
>>> +++ b/arch/i386/pci/mmconfig-shared.c
>>> @@ -72,6 +72,26 @@ static const char __init *pci_mmcfg_e7520(void)
>>>  	return "Intel Corporation E7520 Memory Controller Hub";
>>>  }
>>>
>>> +static const char __init *pci_mmcfg_intel_915(void)
>>> +{
>>> +       u32 pciexbar, len = 0;
>>> +
>>> +       pci_conf1_read(0, 0, PCI_DEVFN(0,0), 0x48, 4, &pciexbar);
>>> +
>>> +       /* No enable bit or size field, so assume 256M range is
>>> enabled. */ +       len = 0x10000000U;
>> Check the 915 spec more carefully, there is an enable bit, it's in
>> the DEVEN register offset 54h, the bit is called PCIEXBAREN (bit 31).
>> If that is not set you should be setting pci_mmcfg_config_num to 0
>> and bailing out.
> 
> Right, but you patch should obsolete this stuff anyway.  I'll test it 
> out in the next few days.

We likely still want this chipset-specific support, it will catch the 
case where the MCFG table lists a location which is reserved in ACPI but 
the chipset was actually programmed to a different location entirely, 
which I seem to remember someone mentioning was actually the case on 
some boards..

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@...pamshaw.ca
Home Page: http://www.roberthancock.com/


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