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Date: Thu, 4 May 2006 14:33:10 -0600
From: Matthew Wilcox <matthew@wil.cx>
To: Rajesh Shah <rajesh.shah@intel.com>
Cc: "Antonino A. Daplas" <adaplas@gmail.com>, Dave Airlie <airlied@gmail.com>,
       gregkh@suse.de, ak@suse.de, linux-pci@atrey.karlin.mff.cuni.cz,
       linux-kernel@vger.kernel.org, akpm@osdl.org,
       Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: i386/x86_84: disable PCI resource decode on device disable
Message-ID: <20060504203310.GE9609@parisc-linux.org>
References: <20060503152747.A29327@unix-os.sc.intel.com> <21d7e9970605032016w2a092ce9qb2bff38e739bca5@mail.gmail.com> <4459CCF5.9080106@gmail.com> <20060504130156.A3494@unix-os.sc.intel.com>
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On Thu, May 04, 2006 at 01:01:57PM -0700, Rajesh Shah wrote:
> Yeah, that's also what some other drivers do. For example, PCI/PCIE
> bridges may support capabilities (like hotplug) that are controlled
> by separate drivers. These drivers don't do pci_disable_device()
> when they unload, since the bridge must continue to decode even
> when the other capability driver is gone.
> 
> The problem is that most PCI bridges don't have any "extra"
> resources padded into the address ranges they pass down. It
> would be nice to be able to reuse address space released when
> a device is disabled (e.g.  for future hot-add), if it's really
> no longer needed.

You could always reprogram the BARs.  But I really wouldn't recommend
this; you'll just fragment the address space.