linux-kernel - Re: [PATCH 08/14] pci: update bridge res to get more big range in pci assign unssign

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Message-ID: <4B50DA47.80800@kernel.org>
Date:	Fri, 15 Jan 2010 13:12:39 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Jesse Barnes <jbarnes@...tuousgeek.org>
CC:	Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ivan Kokshaysky <ink@...assic.park.msu.ru>,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
	Alex Chiang <achiang@...com>,
	Bjorn Helgaas <bjorn.helgaas@...com>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH 08/14] pci: update bridge res to get more big range in
 pci assign unssign

On 01/15/2010 11:12 AM, Jesse Barnes wrote:
> On Tue, 22 Dec 2009 15:02:28 -0800
> Yinghai Lu <yinghai@...nel.org> wrote:
> 
>> BIOS separate IO range between several IOHs, and on some slots, BIOS
>> assign the resource to the bridge, but stop assigning resource to the
>> device under that bridge, because the device need big resource.
>>
>> 1. pci assign unassign and record the failed device resource.
>> 2. clear the BIOS assigned resource of the parent bridge of fail
>> device 3. go back and call pci assign unsigned
>> 4. if it still fail, will go up more bridges. and clear and try again.
>>
>> use pci_try_num to control back track bridge levels.
>>
>> -v2: update it with resource_list_x
>> -v3: make pci_try_num default to 1. and when pci_try_num is set to
>> more than 1 will check it with max_depth, and adjust that to make
>> sure it is bigger enough
> 
> I really don't like the 'try' argument.  Either we can assign the
> resource or not; 'try=' just makes the whole thing scarier, as if we
> expect problems if we release too many resources.  If that's the case,
> then the whole approach must be flawed, since it means we're not taking
> into account some resources, or we're missing something about the
> system configuration.

before this patchset, acctually try = 1, and will not touch pci bridge resource if that are assigned by BIOS.

with this patchset, try = 1, will just like the old ways.
try = 2, it will find the deepest bridge, and increase the try.

YH
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