On Tue, Jul 13, 2021 at 08:50:07PM +0800, Kai-Heng Feng wrote:
> 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.
>
> This is the second take of commit 65db04053efe ("PCI: Coalesce host
> bridge contiguous apertures"). The original approach sorts the apertures
> by address, but that makes NVMe stop working on QEMU ppc:sam460ex:
> PCI host bridge to bus 0002:00
> pci_bus 0002:00: root bus resource [io 0x0000-0xffff]
> pci_bus 0002:00: root bus resource [mem 0xd80000000-0xdffffffff] (bus address [0x80000000-0xffffffff])
> pci_bus 0002:00: root bus resource [mem 0xc0ee00000-0xc0eefffff] (bus address [0x00000000-0x000fffff])
>
> After the offending commit:
> PCI host bridge to bus 0002:00
> pci_bus 0002:00: root bus resource [io 0x0000-0xffff]
> pci_bus 0002:00: root bus resource [mem 0xc0ee00000-0xc0eefffff] (bus address [0x00000000-0x000fffff])
> pci_bus 0002:00: root bus resource [mem 0xd80000000-0xdffffffff] (bus address [0x80000000-0xffffffff])
>
> Since the apertures on HP EliteDesk 805 G6 are already in ascending
> order, doing a precautious sorting is not necessary.
>
> Remove the sorting part to avoid the regression on ppc:sam460ex.
>
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212013
> Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
> Suggested-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
Applied to pci/resource for v5.16, thanks!
> ---
> v2:
> - Bring back the original commit message.
>
> drivers/pci/probe.c | 31 +++++++++++++++++++++++++++----
> 1 file changed, 27 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 79177ac37880..5de157600466 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -877,11 +877,11 @@ static void pci_set_bus_msi_domain(struct pci_bus *bus)
> 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;
> @@ -961,11 +961,34 @@ 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");
>
> + /* Coalesce contiguous windows */
> + 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);
> --
> 2.31.1
>
