From: Jeremy Linton <jeremy.linton@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-acpi@vger.kernel.org, catalin.marinas@arm.com,
will@kernel.org, rjw@rjwysocki.net, lenb@kernel.org,
lorenzo.pieralisi@arm.com, sudeep.holla@arm.com, rric@kernel.org,
Jeremy Linton <jeremy.linton@arm.com>
Subject: [PATCH v4 2/2] arm64: topology: Use PPTT to determine if PE is a thread
Date: Thu, 8 Aug 2019 15:40:07 -0500 [thread overview]
Message-ID: <20190808204007.30110-3-jeremy.linton@arm.com> (raw)
In-Reply-To: <20190808204007.30110-1-jeremy.linton@arm.com>
ACPI 6.3 adds a thread flag to represent if a CPU/PE is
actually a thread. Given that the MPIDR_MT bit may not
represent this information consistently on homogeneous machines
we should prefer the PPTT flag if its available.
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
---
arch/arm64/kernel/topology.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
index 0825c4a856e3..bad9c42ea825 100644
--- a/arch/arm64/kernel/topology.c
+++ b/arch/arm64/kernel/topology.c
@@ -340,17 +340,28 @@ void remove_cpu_topology(unsigned int cpu)
}
#ifdef CONFIG_ACPI
+static int __init acpi_cpu_is_threaded(int cpu)
+{
+ int is_threaded = acpi_pptt_cpu_is_thread(cpu);
+
+ /*
+ * if the PPTT doesn't have thread information, assume a homogeneous
+ * machine and return the current CPU's thread state.
+ */
+ if (is_threaded < 0)
+ is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK;
+
+ return is_threaded;
+}
+
/*
* Propagate the topology information of the processor_topology_node tree to the
* cpu_topology array.
*/
static int __init parse_acpi_topology(void)
{
- bool is_threaded;
int cpu, topology_id;
- is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK;
-
for_each_possible_cpu(cpu) {
int i, cache_id;
@@ -358,7 +369,7 @@ static int __init parse_acpi_topology(void)
if (topology_id < 0)
return topology_id;
- if (is_threaded) {
+ if (acpi_cpu_is_threaded(cpu)) {
cpu_topology[cpu].thread_id = topology_id;
topology_id = find_acpi_cpu_topology(cpu, 1);
cpu_topology[cpu].core_id = topology_id;
--
2.21.0
next prev parent reply other threads:[~2019-08-08 20:41 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-08 20:40 [PATCH v4 0/2] arm64/PPTT ACPI 6.3 thread flag support Jeremy Linton
2019-08-08 20:40 ` [PATCH v4 1/2] ACPI/PPTT: Add support for ACPI 6.3 thread flag Jeremy Linton
2019-08-08 22:25 ` Robert Richter
2019-08-12 9:06 ` Rafael J. Wysocki
2019-08-12 11:59 ` Will Deacon
2019-08-20 9:01 ` John Garry
2019-08-21 13:20 ` Jeremy Linton
2019-08-21 13:25 ` John Garry
2019-08-08 20:40 ` Jeremy Linton [this message]
2019-08-08 22:23 ` [PATCH v4 2/2] arm64: topology: Use PPTT to determine if PE is a thread Robert Richter
-- strict thread matches above, loose matches on Subject: below --
2019-08-01 3:46 [PATCH v4 0/2] arm64/PPTT ACPI 6.3 thread flag support Jeremy Linton
2019-08-01 3:46 ` [PATCH v4 2/2] arm64: topology: Use PPTT to determine if PE is a thread Jeremy Linton
2019-08-01 15:58 ` Sudeep Holla
2019-08-02 13:44 ` Robert Richter
2019-08-02 16:04 ` Jeremy Linton
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