On Thu, Apr 1, 2021 at 9:12 PM Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> wrote: > > Built-in graphics on HP EliteDesk 805 G6 doesn't work because graphics > can't get the BAR it needs: > [ 0.611504] pci_bus 0000:00: root bus resource [mem 0x10020200000-0x100303fffff window] > [ 0.611505] pci_bus 0000:00: root bus resource [mem 0x10030400000-0x100401fffff window] > ... > [ 0.638083] pci 0000:00:08.1: bridge window [mem 0xd2000000-0xd23fffff] > [ 0.638086] pci 0000:00:08.1: bridge window [mem 0x10030000000-0x100401fffff 64bit pref] > [ 0.962086] pci 0000:00:08.1: can't claim BAR 15 [mem 0x10030000000-0x100401fffff 64bit pref]: no compatible bridge window > [ 0.962086] pci 0000:00:08.1: [mem 0x10030000000-0x100401fffff 64bit pref] clipped to [mem 0x10030000000-0x100303fffff 64bit pref] > [ 0.962086] pci 0000:00:08.1: bridge window [mem 0x10030000000-0x100303fffff 64bit pref] > [ 0.962086] pci 0000:07:00.0: can't claim BAR 0 [mem 0x10030000000-0x1003fffffff 64bit pref]: no compatible bridge window > [ 0.962086] 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 regions that can contain the > child resource requested. > > Bjorn Helgaas pointed out that we can simply coalesce contiguous regions > for host bridges, since host bridge don't have _SRS. So do that > accordingly to make child resource can be contained. This change makes > the graphics works on the system in question. > > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212013 > Suggested-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> A gentle ping... > --- > v2: > - Coalesce all contiguous regresion in pci_register_host_bridge(), if > conditions are met. > > drivers/pci/probe.c | 49 +++++++++++++++++++++++++++++++++++++++++---- > 1 file changed, 45 insertions(+), 4 deletions(-) > > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c > index 953f15abc850..3607ce7402b4 100644 > --- a/drivers/pci/probe.c > +++ b/drivers/pci/probe.c > @@ -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 +875,30 @@ static void pci_set_bus_msi_domain(struct pci_bus *bus) > dev_set_msi_domain(&bus->dev, d); > } > > +static int res_cmp(void *priv, struct list_head *a, 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; > @@ -959,11 +976,35 @@ 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); > -- > 2.30.2 >
