From: Ard Biesheuvel ard.biesheuvel@linaro.org
[ Upstream commit 2af22f3ec3ca452f1e79b967f634708ff01ced8a ]
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.
Acked-by: Sudeep Holla sudeep.holla@arm.com Tested-by: Lee Jones lee.jones@linaro.org Reviewed-by: Graeme Gregory graeme.gregory@linaro.org Acked-by: Lorenzo Pieralisi lorenzo.pieralisi@arm.com Acked-by: Hanjun Guo guohanjun@huawei.com Signed-off-by: Ard Biesheuvel ard.biesheuvel@linaro.org Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 d1ce8e2f98b9..4d0577d09681 100644 --- a/arch/arm64/kernel/acpi.c +++ b/arch/arm64/kernel/acpi.c @@ -141,10 +141,14 @@ 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)) {