Commit 94867573 authored Jan 06, 2020 by Nicholas Johnson Committed by Bjorn Helgaas Jan 29, 2020

PCI: Allow adjust_bridge_window() to shrink resource if necessary

Remove checks for resource size in adjust_bridge_window(). This is
necessary to allow pci_bus_distribute_available_resources() to function
when the kernel parameter "pci=hpmemsize=nn[KMG]" is used to allocate
resources. Because the kernel parameter sets the size of all hotplug
bridges to be the same, there are problems when nested hotplug bridges are
encountered. Fitting a downstream hotplug bridge with size X and normal
bridges with non-zero size Y into parent hotplug bridge with size X is
impossible, and hence the downstream hotplug bridge needs to shrink to fit
into its parent.

Add check for if bridge is extended or shrunken and reflect that in the
call to pci_dbg().

Reset the resource if its new size is zero (if we have run out of a bridge
window resource) to prevent the PCI resource assignment code from
attempting to assign a zero-sized resource.

Link: https://lore.kernel.org/r/PSXP216MB0438D3E2CFE64EBAA32AF691803C0@PSXP216MB0438.KORP216.PROD.OUTLOOK.COM

Signed-off-by: Nicholas Johnson <nicholas.johnson-opensource@outlook.com.au>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>

parent ae4611f1

drivers/pci/setup-bus.c

+12 −4

Original line number	Diff line number	Diff line
		@@ -1842,16 +1842,24 @@ static void adjust_bridge_window(struct pci_dev bridge, struct resource res,
		struct list_head *add_list,
		resource_size_t new_size)
		{
		resource_size_t add_size;
		resource_size_t add_size, size = resource_size(res);

		if (res->parent)
		return;

		if (resource_size(res) >= new_size)
		if (!new_size)
		return;

		add_size = new_size - resource_size(res);
		pci_dbg(bridge, "bridge window %pR extended by %pa\n", res, &add_size);
		if (new_size > size) {
		add_size = new_size - size;
		pci_dbg(bridge, "bridge window %pR extended by %pa\n", res,
		&add_size);
		} else if (new_size < size) {
		add_size = size - new_size;
		pci_dbg(bridge, "bridge window %pR shrunken by %pa\n", res,
		&add_size);
		}

		res->end = res->start + new_size - 1;
		remove_from_list(add_list, res);
		}

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