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From: Jeremy Linton <jeremy.linton@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: catalin.marinas@arm.com, will.deacon@arm.com, rjw@rjwysocki.net,
	linux-kernel@vger.kernel.org,
	Jeremy Linton <jeremy.linton@arm.com>,
	linux-acpi@vger.kernel.org, sudeep.holla@arm.com,
	lenb@kernel.org
Subject: [PATCH v2 2/2] arm64: topology: Use PPTT to determine if PE is a thread
Date: Fri, 14 Jun 2019 17:31:58 -0500
Message-ID: <20190614223158.49575-3-jeremy.linton@arm.com> (raw)
In-Reply-To: <20190614223158.49575-1-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>
---
 arch/arm64/kernel/topology.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
index 0825c4a856e3..cbbedb53cf06 100644
--- a/arch/arm64/kernel/topology.c
+++ b/arch/arm64/kernel/topology.c
@@ -346,11 +346,9 @@ void remove_cpu_topology(unsigned int cpu)
  */
 static int __init parse_acpi_topology(void)
 {
-	bool is_threaded;
+	int is_threaded;
 	int cpu, topology_id;
 
-	is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK;
-
 	for_each_possible_cpu(cpu) {
 		int i, cache_id;
 
@@ -358,6 +356,10 @@ static int __init parse_acpi_topology(void)
 		if (topology_id < 0)
 			return topology_id;
 
+		is_threaded = acpi_pptt_cpu_is_thread(cpu);
+		if (is_threaded < 0)
+			is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK;
+
 		if (is_threaded) {
 			cpu_topology[cpu].thread_id = topology_id;
 			topology_id = find_acpi_cpu_topology(cpu, 1);
-- 
2.21.0


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Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-14 22:31 [PATCH v2 0/2] arm64/PPTT ACPI 6.3 thread flag support Jeremy Linton
2019-06-14 22:31 ` [PATCH v2 1/2] ACPI/PPTT: Add support for ACPI 6.3 thread flag Jeremy Linton
2019-06-17 12:34   ` Valentin Schneider
2019-06-18 14:21     ` Jeremy Linton
2019-06-18 14:40       ` Valentin Schneider
2019-06-18 17:23         ` John Garry
2019-06-18 21:28           ` Jeremy Linton
2019-06-19  9:15             ` John Garry
2019-06-14 22:31 ` Jeremy Linton [this message]

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