[RFC 1/1] PCI/ACPI: Make acpi_pci_root_validate_resources() reject IOMEM resources which start at address 0

Hans de Goede
2021-06-15T10:26:11Z

On some Lenovo laptops the base-addrsss of some PCI devices is left
at 0 at boot:

[ 0.283145] pci 0000:00:15.0: [8086:34e8] type 00 class 0x0c8000
[ 0.283217] pci 0000:00:15.0: reg 0x10: [mem 0x00000000-0x00000fff 64bit]
[ 0.285117] pci 0000:00:15.1: [8086:34e9] type 00 class 0x0c8000
[ 0.285189] pci 0000:00:15.1: reg 0x10: [mem 0x00000000-0x00000fff 64bit]

There is a _CRS method for these devices, which simply returns the
configured 0 address. This is causing the PCI core to not assign
memory to these PCI devices and is causing these errors:

[ 0.655335] pci 0000:00:15.0: BAR 0: no space for [mem size 0x00001000 64bit]
[ 0.655337] pci 0000:00:15.0: BAR 0: failed to assign [mem size 0x00001000 64bit]
[ 0.655339] pci 0000:00:15.1: BAR 0: no space for [mem size 0x00001000 64bit]
[ 0.655340] pci 0000:00:15.1: BAR 0: failed to assign [mem size 0x00001000 64bit]

This happens specifically for the designware I2C PCI devices on these
laptops, causing I2C-HID attached touchpads/touchscreens to not work.

Booting with nocrs on these devices results in the kernel itself
assigning memory to these devices, fixing things:

[ 0.355716] pci 0000:00:15.0: BAR 0: assigned [mem 0x29c000000-0x29c000fff 64bit]
[ 0.355783] pci 0000:00:15.1: BAR 0: assigned [mem 0x29c001000-0x29c001fff 64bit]

At least the following models are known to be affected by this (but there
might be more):

Lenovo IdeaPad 3 15IIL05 81WE
Lenovo IdeaPad 5 14IIL05 81YH

Add an extra check for the base-address being 0 to
acpi_pci_root_validate_resources() and reject IOMEM resources where this
is the case, to fix this issue.

BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1871793
BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1868899
BugLink: https://bugs.launchpad.net/ubuntu/+source/linux-signed-hwe/+bug/1878279
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Note we could instead add the known to be affected models to the
pci_crs_quirks table in arch/x86/pci/acpi.c, but it is likely that more
systems are affected and a more generic fix seems better in general.
---
drivers/acpi/pci_root.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index dcd593766a64..6cd2ca551005 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -686,6 +686,13 @@ static void acpi_pci_root_validate_resources(struct device *dev,
if (!(res1->flags & type))
goto next;

+ if ((type & IORESOURCE_MEM) && res1->start == 0) {
+ dev_info(dev, "host bridge window %pR (ignored, start address not set)\n",
+ res1);
+ free = true;
+ goto next;
+ }
+
/* Exclude non-addressable range or non-addressable portion */
end = min(res1->end, root->end);
if (end <= res1->start) {
--
2.31.1