[PATCH] arm64: PCI: Add quirk for platforms running Windows

Shawn Guo
2023-02-27T02:19:16Z

Commit 8fd4391ee717 ("arm64: PCI: Exclude ACPI "consumer" resources from
host bridge windows") introduced a check to remove host bridge register
resources for all arm64 platforms, with the assumption that the PNP0A03
_CRS resources would always be host bridge registers and never as windows
on arm64.

The assumption stands true until Qualcomm Snapdragon Windows laptops
emerge. These laptops describe host bridge windows in PNP0A03 _CRS
resources instead. For example, the Microsoft Surface Pro X has host
bridges defined as

Name (_HID, EisaId ("PNP0A08") /* PCI Express Bus */) // _HID: Hardware ID
Name (_CID, EisaId ("PNP0A03") /* PCI Bus */) // _CID: Compatible ID

Method (_CRS, 0, NotSerialized) // _CRS: Current Resource Settings
{
Name (RBUF, ResourceTemplate ()
{
Memory32Fixed (ReadWrite,
0x60200000, // Address Base
0x01DF0000, // Address Length
)
WordBusNumber (ResourceProducer, MinFixed, MaxFixed, PosDecode,
0x0000, // Granularity
0x0000, // Range Minimum
0x0001, // Range Maximum
0x0000, // Translation Offset
0x0002, // Length
,, )
})
Return (RBUF) /* \_SB_.PCI0._CRS.RBUF */
}

The Memory32Fixed holds a host bridge window, but it's not properly
defined as a "producer" resource. Consequently the resource gets
removed by kernel, and the BAR allocation fails later on:

[ 0.150731] pci 0002:00:00.0: BAR 14: no space for [mem size 0x00100000]
[ 0.150744] pci 0002:00:00.0: BAR 14: failed to assign [mem size 0x00100000]
[ 0.150758] pci 0002:01:00.0: BAR 0: no space for [mem size 0x00004000 64bit]
[ 0.150769] pci 0002:01:00.0: BAR 0: failed to assign [mem size 0x00004000 64bit]

This eventually prevents the PCIe NVME drive from being accessible.

Add a quirk for these platforms to avoid the resource being removed.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
---
We are running into the issue on more devices than just Surface Pro X
now, so trying to sort it out with a quirk as suggested by Lorenzo [1].

[1] https://lore.kernel.org/all/20210527093200.GA16444@lpieralisi/

arch/arm64/kernel/pci.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)

diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
index 2276689b5411..896dbd028b67 100644
--- a/arch/arm64/kernel/pci.c
+++ b/arch/arm64/kernel/pci.c
@@ -109,16 +109,42 @@ int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
return 0;
}

+#define QCOM_DSDT_QUIRK "Host bridge windows in PNP0A03 _CRS"
+
+static struct acpi_platform_list qcom_platlist[] = {
+ /* Thinkpad X13s */
+ { "LENOVO", "SDM8280 ", 0, ACPI_SIG_DSDT, all_versions, QCOM_DSDT_QUIRK },
+ /* Microsoft Surface Pro 9 (5G) and Windows Dev Kit 2023 */
+ { "QCOMM ", "SDM8280 ", 0, ACPI_SIG_DSDT, all_versions, QCOM_DSDT_QUIRK },
+ /* Microsoft Surface Pro X */
+ { "QCOMM ", "SDM8180 ", 0, ACPI_SIG_DSDT, all_versions, QCOM_DSDT_QUIRK },
+ { }
+};
+
static int pci_acpi_root_prepare_resources(struct acpi_pci_root_info *ci)
{
struct resource_entry *entry, *tmp;
int status;
+ int idx;

status = acpi_pci_probe_root_resources(ci);
+
+ /*
+ * Most arm64 platforms that do not run Windows describe host bridge
+ * registers in PNP0A03 _CRS resources, but some like Qualcomm
+ * Snapdragon Windows laptops describe host bridge windows in there.
+ * We do not want to destroy the resources for these platforms.
+ */
+ idx = acpi_match_platform_list(qcom_platlist);
+ if (idx >= 0)
+ goto done;
+
resource_list_for_each_entry_safe(entry, tmp, &ci->resources) {
if (!(entry->res->flags & IORESOURCE_WINDOW))
resource_list_destroy_entry(entry);
}
+
+done:
return status;
}

--
2.17.1