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x86/PCI: revert "Ignore E820 reservations for bridge windows on newer systems"

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Commit 7f7b4236f2 ("x86/PCI: Ignore E820 reservations for bridge windows
on newer systems") fixes the touchpad not working on laptops like
the Lenovo IdeaPad 3 15IIL05 and the Lenovo IdeaPad 5 14IIL05, as well as
fixing thunderbolt hotplug issues on the Lenovo Yoga C940.

Unfortunately it turns out that this is causing issues with suspend/resume
on Lenovo ThinkPad X1 Carbon Gen 2 laptops. So, per the no regressions
policy, rever this. Note I'm looking into another fix for the issues this
fixed.

Fixes: 7f7b4236f2 ("x86/PCI: Ignore E820 reservations for bridge windows on newer systems")
BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=2029207
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Hans de Goede 2022-02-09 17:13:42 +01:00 committed by Rafael J. Wysocki
parent 7f7b4236f2
commit 3eb616b264
1 changed files with 1 additions and 22 deletions
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23
arch/x86/kernel/resource.c
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@ -1,5 +1,4 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/dmi.h>
#include <linux/ioport.h>
#include <asm/e820/api.h>
@ -24,31 +23,11 @@ static void resource_clip(struct resource *res, resource_size_t start,
res->start = end + 1;
}
/*
* Some BIOS-es contain a bug where they add addresses which map to
* system RAM in the PCI host bridge window returned by the ACPI _CRS
* method, see commit 4dc2287c1805 ("x86: avoid E820 regions when
* allocating address space"). To avoid this Linux by default excludes
* E820 reservations when allocating addresses since 2010.
* In 2019 some systems have shown-up with E820 reservations which cover
* the entire _CRS returned PCI host bridge window, causing all attempts
* to assign memory to PCI BARs to fail if Linux uses E820 reservations.
*
* Ideally Linux would fully stop using E820 reservations, but then
* the old systems this was added for will regress.
* Instead keep the old behavior for old systems, while ignoring the
* E820 reservations for any systems from now on.
*/
static void remove_e820_regions(struct resource *avail)
{
int i, year = dmi_get_bios_year();
int i;
struct e820_entry *entry;
if (year >= 2018)
return;
pr_info_once("PCI: Removing E820 reservations from host bridge windows\n");
for (i = 0; i < e820_table->nr_entries; i++) {
entry = &e820_table->entries[i];