ACPICA: executer/exsystem: Inform users about ACPI spec violation

ACPICA commit 05ba545ce7859392250b18c10081db25c90ed8d7

Values greater than 100 microseconds violate the ACPI specification, so
warn users about it.

From ACPI Specification version 6.2 Errata A, 19.6.128 *Stall (Stall for
a Short Time)*:

> The implementation of Stall is OS-specific, but must not relinquish
> control of the processor. Because of this, delays longer than 100
> microseconds must use Sleep instead of Stall.

Link: https://github.com/acpica/acpica/commit/05ba545c
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reported-by: kernel test robot <lkp@intel.com>

diff --git a/drivers/acpi/acpica/exsystem.c b/drivers/acpi/acpica/exsystem.c
index 7d19f2398b51ef221c98c9a0a7eb9342eff1b169..754cf289fc01e9e0be7774d283ded441a4495e42 100644 (file)
--- a/drivers/acpi/acpica/exsystem.c
+++ b/drivers/acpi/acpica/exsystem.c
@@ -137,6 +137,11 @@ acpi_status acpi_ex_system_do_stall(u32 how_long_us)
                            "Time parameter is too large (%u)", how_long_us));
                status = AE_AML_OPERAND_VALUE;
        } else {
+               if (how_long_US > 100) {
+                       ACPI_WARNING((AE_INFO,
+                                     "Time parameter %u us > 100 us violating ACPI spec, please fix the firmware.",
+                                     how_long_us));
+               }
                acpi_os_stall(how_long_us);
        }