From a7edc17544709d20f800dc0898096365a3d68613 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Sun, 2 Jun 2019 16:36:15 +0200 Subject: [PATCH] acpi/arm64: ignore 5.1 FADTs that are reported as 5.0 Some Qualcomm Snapdragon based laptops built to run Microsoft Windows are clearly ACPI 5.1 based, given that that is the first ACPI revision that supports ARM, and introduced the FADT 'arm_boot_flags' field, which has a non-zero field on those systems. So in these cases, infer from the ARM boot flags that the FADT must be 5.1 or later, and treat it as 5.1. Signed-off-by: Ard Biesheuvel --- arch/arm64/kernel/acpi.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c index 803f0494dd3e3..7722e85fb69c3 100644 --- a/arch/arm64/kernel/acpi.c +++ b/arch/arm64/kernel/acpi.c @@ -155,10 +155,14 @@ static int __init acpi_fadt_sanity_check(void) */ if (table->revision < 5 || (table->revision == 5 && fadt->minor_revision < 1)) { - pr_err("Unsupported FADT revision %d.%d, should be 5.1+\n", + pr_err(FW_BUG "Unsupported FADT revision %d.%d, should be 5.1+\n", table->revision, fadt->minor_revision); - ret = -EINVAL; - goto out; + + if (!fadt->arm_boot_flags) { + ret = -EINVAL; + goto out; + } + pr_err("FADT has ARM boot flags set, assuming 5.1\n"); } if (!(fadt->flags & ACPI_FADT_HW_REDUCED)) {