Commit 65db0405 authored by Kai-Heng Feng's avatar Kai-Heng Feng Committed by Bjorn Helgaas
Browse files

PCI: Coalesce host bridge contiguous apertures 

Built-in graphics on HP EliteDesk 805 G6 doesn't work because graphics
can't get the BAR it needs:

  pci_bus 0000:00: root bus resource [mem 0x10020200000-0x100303fffff window]
  pci_bus 0000:00: root bus resource [mem 0x10030400000-0x100401fffff window]

  pci 0000:00:08.1:   bridge window [mem 0xd2000000-0xd23fffff]
  pci 0000:00:08.1:   bridge window [mem 0x10030000000-0x100401fffff 64bit pref]
  pci 0000:00:08.1: can't claim BAR 15 [mem 0x10030000000-0x100401fffff 64bit pref]: no compatible bridge window
  pci 0000:00:08.1: [mem 0x10030000000-0x100401fffff 64bit pref] clipped to [mem 0x10030000000-0x100303fffff 64bit pref]
  pci 0000:00:08.1:   bridge window [mem 0x10030000000-0x100303fffff 64bit pref]
  pci 0000:07:00.0: can't claim BAR 0 [mem 0x10030000000-0x1003fffffff 64bit pref]: no compatible bridge window
  pci 0000:07:00.0: can't claim BAR 2 [mem 0x10040000000-0x100401fffff 64bit pref]: no compatible bridge window

However, the root bus has two contiguous apertures that can contain the
child resource requested.

Coalesce contiguous apertures so we can allocate from the entire contiguous
region.

[bhelgaas: fold in https://lore.kernel.org/r/20210528170242.1564038-1-kai.heng.feng@canonical.com]
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212013


Suggested-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20210401131252.531935-1-kai.heng.feng@canonical.com


Signed-off-by: default avatarKai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent 6efb943b

drivers/pci/probe.c

+46 −4
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#include <linux/hypervisor.h>

#include <linux/irqdomain.h>

#include <linux/pm_runtime.h>

#include <linux/list_sort.h>

#include "pci.h"



#define CARDBUS_LATENCY_TIMER	176	/* secondary latency timer */
@@ -874,14 +875,31 @@ static void pci_set_bus_msi_domain(struct pci_bus *bus) 
	dev_set_msi_domain(&bus->dev, d);

}



static int res_cmp(void *priv, const struct list_head *a,

		   const struct list_head *b)

{

	struct resource_entry *entry1, *entry2;



	entry1 = container_of(a, struct resource_entry, node);

	entry2 = container_of(b, struct resource_entry, node);



	if (entry1->res->flags != entry2->res->flags)

		return entry1->res->flags > entry2->res->flags;



	if (entry1->offset != entry2->offset)

		return entry1->offset > entry2->offset;



	return entry1->res->start > entry2->res->start;

}



static int pci_register_host_bridge(struct pci_host_bridge *bridge)

{

	struct device *parent = bridge->dev.parent;

	struct resource_entry *window, *n;

	struct resource_entry *window, *next, *n;

	struct pci_bus *bus, *b;

	resource_size_t offset;

	resource_size_t offset, next_offset;

	LIST_HEAD(resources);

	struct resource *res;

	struct resource *res, *next_res;

	char addr[64], *fmt;

	const char *name;

	int err;
@@ -960,11 +978,35 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge) 
	if (nr_node_ids > 1 && pcibus_to_node(bus) == NUMA_NO_NODE)

		dev_warn(&bus->dev, "Unknown NUMA node; performance will be reduced\n");



	/* Sort and coalesce contiguous windows */

	list_sort(NULL, &resources, res_cmp);

	resource_list_for_each_entry_safe(window, n, &resources) {

		if (list_is_last(&window->node, &resources))

			break;



		next = list_next_entry(window, node);

		offset = window->offset;

		res = window->res;

		next_offset = next->offset;

		next_res = next->res;



		if (res->flags != next_res->flags || offset != next_offset)

			continue;



		if (res->end + 1 == next_res->start) {

			next_res->start = res->start;

			res->flags = res->start = res->end = 0;

		}

	}



	/* Add initial resources to the bus */

	resource_list_for_each_entry_safe(window, n, &resources) {

		list_move_tail(&window->node, &bridge->windows);

		offset = window->offset;

		res = window->res;

		if (!res->end)

			continue;



		list_move_tail(&window->node, &bridge->windows);



		if (res->flags & IORESOURCE_BUS)

			pci_bus_insert_busn_res(bus, bus->number, res->end);