[PATCH 1/1] cxl/acpi.c: Add buggy BIOS hint for CXL ACPI lookup failure

ppwaskie
2024-04-07T21:05:51Z

From: PJ Waskiewicz <ppwaskie@kernel.org>

Currently, Type 3 CXL devices (CXL.mem) can train using host CXL
drivers on Emerald Rapids systems. However, on some production
systems from some vendors, a buggy BIOS exists that improperly
populates the ACPI => PCI mappings. This leads to the cxl_acpi
driver to fail probe when it cannot find the root port's _UID, in
order to look up the device's CXL attributes in the CEDT.

Add a bit more of a descriptive message that the lookup failure
could be a bad BIOS, rather than just "failed."

Signed-off-by: PJ Waskiewicz <ppwaskie@kernel.org>
---
drivers/cxl/acpi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index af5cb818f84d..56019466a09c 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -504,7 +504,7 @@ static int cxl_get_chbs(struct device *dev, struct acpi_device *hb,

rc = acpi_evaluate_integer(hb->handle, METHOD_NAME__UID, NULL, &uid);
if (rc != AE_OK) {
- dev_err(dev, "unable to retrieve _UID\n");
+ dev_err(dev, "unable to retrieve _UID. Potentially buggy BIOS\n");
return -ENOENT;
}

--
2.40.1