Re: [PATCH 10/11] pciehp: add support for bridge resource reallocation

Jesse Barnes
2010-01-17T17:34:18Z

On Sat, 16 Jan 2010 16:14:31 -0700
Bjorn Helgaas <bjorn.helgaas@hp.com> wrote:

> On Sat, 2010-01-16 at 01:34 -0800, Yinghai Lu wrote:
> > On 01/15/2010 08:59 PM, Alex Chiang wrote:
> > > * Yinghai Lu <yinghai@kernel.org>:
> > >> From: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
> > >>
> > >> With this patch, pciehp driver try to clear PCI bridge resources
> > >> to parent bridge (root port or switch downstream port) of the
> > >> slot
> > >>
> > >> so we can shrink pci bridge resource for those port
> > >>
> > >> This feature is enabled when 'pciehp_realloc' option is
> > >> specified.
> > >>
> > >> -v2: make it could be appiled after Yinghai patchset that touch
> > >> pci bridge resource also remove poweron check, because
> > >> pci_bridge_release_res will check child at first
> > >
> > > Same comment as my earlier patch. Why not just make this the
> > > default behavior, instead of introducing yet another command line
> > > parameter for users to guess at?
> >
> > it will break Eric's setup/
>
> I think this is a clue that we don't understand the problem well
> enough yet.
>
> I'm opposed to adding kernel parameters for this sort of thing. It is
> unreasonable to expect users to figure out whether they need to use
> this parameter or not.
>
> Special-case switches like this make it much harder to maintain the
> code in the future.

Agreed. Yinghai, what's wrong in the new reassignment code that
causes Eric's setup to break? Can we just fix that instead and enable
reallocation by default?

--
Jesse Barnes, Intel Open Source Technology Center