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Message-ID: <5a259297eeca3484565faf3166b2e4019047b478.camel@kernel.crashing.org>
Subject: Re: Question about call to pci_assign_unassigned_bus_resources in
 amdgpu
From:   Benjamin Herrenschmidt <benh@kernel.crashing.org>
To:     "Koenig, Christian" <Christian.Koenig@amd.com>
Cc:     "Deucher, Alexander" <Alexander.Deucher@amd.com>,
        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>
Date:   Mon, 24 Jun 2019 18:56:42 +1000
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On Mon, 2019-06-24 at 18:47 +1000, Benjamin Herrenschmidt wrote:
> On Mon, 2019-06-24 at 08:42 +0000, Koenig, Christian wrote:
> > Then we resize the VRAM BAR by calling pci_resize_resource(). That in 
> > turn tries to resize and shuffle around the parent bridge resources 
> > using pci_reassign_bridge_resources().
> > 
> > But pci_reassign_bridge_resources() does not assign any device 
> > resources, it just tries to make sure the upstream bridges have enough 
> > space to fit everything in.

Hrm... are you sure of this ? Maybe it has changed... or I'm missing
something. Because right in the middle of it I see:


 	__pci_bus_size_bridges(bridge->subordinate, &added);
	__pci_bridge_assign_resources(bridge, &added, &failed);

Now the second of these will call __pci_bus_assign_resources() on the
bridge->subordinate, which will recursively assign all devices below
the bridge.

Or am I overlooking something ?

It could be that if it fails, then you need to restore your device
resources indeed... but the normal case should work from my reading of
the code.

Cheers,
Ben.