5.0-stable review patch. If anyone has any objections, please let me know.
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From: Srinivas Pandruvada srinivas.pandruvada@linux.intel.com
commit edef1ef134180149694b86386277076f566d165c upstream.
As per the ACPI specification, "Guaranteed Performance Register" is a "Buffer" field and it cannot be "Integer", so treat the "Integer" type for "Guaranteed Performance Register" field as invalid and ignore its value in that case.
Also save one cpc_read() call when "Guaranteed Performance Register" is not present, which means a register defined as: "Register(SystemMemory, 0, 0, 0, 0)".
Fixes: 29523f095397 ("ACPI / CPPC: Add support for guaranteed performance") Suggested-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Srinivas Pandruvada srinivas.pandruvada@linux.intel.com Cc: 4.20+ stable@vger.kernel.org # 4.20+ Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/acpi/cppc_acpi.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
--- a/drivers/acpi/cppc_acpi.c +++ b/drivers/acpi/cppc_acpi.c @@ -1108,8 +1108,13 @@ int cppc_get_perf_caps(int cpunum, struc cpc_read(cpunum, nominal_reg, &nom); perf_caps->nominal_perf = nom;
- cpc_read(cpunum, guaranteed_reg, &guaranteed); - perf_caps->guaranteed_perf = guaranteed; + if (guaranteed_reg->type != ACPI_TYPE_BUFFER || + IS_NULL_REG(&guaranteed_reg->cpc_entry.reg)) { + perf_caps->guaranteed_perf = 0; + } else { + cpc_read(cpunum, guaranteed_reg, &guaranteed); + perf_caps->guaranteed_perf = guaranteed; + }
cpc_read(cpunum, lowest_non_linear_reg, &min_nonlinear); perf_caps->lowest_nonlinear_perf = min_nonlinear;