linux-kernel - [PATCH] ARC: perf: don't bail setup if pct irq missing in device-tree

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Message-Id: <20200727051345.13382-1-vgupta@synopsys.com>
Date:   Sun, 26 Jul 2020 22:13:45 -0700
From:   Vineet Gupta <Vineet.Gupta1@...opsys.com>
To:     linux-snps-arc@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>,
        Vineet Gupta <Vineet.Gupta1@...opsys.com>
Subject: [PATCH] ARC: perf: don't bail setup if pct irq missing in device-tree

Current code inadventely bails if hardware supports sampling/overflow
interrupts, but the irq is missing from device tree. This need not be as
we can still do simple counting based perf stat.

This unborks perf on HSDK-4xD

Signed-off-by: Vineet Gupta <vgupta@...opsys.com>
---
 arch/arc/kernel/perf_event.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/arch/arc/kernel/perf_event.c b/arch/arc/kernel/perf_event.c
index 661fd842ea97..79849f37e782 100644
--- a/arch/arc/kernel/perf_event.c
+++ b/arch/arc/kernel/perf_event.c
@@ -562,7 +562,7 @@ static int arc_pmu_device_probe(struct platform_device *pdev)
 {
 	struct arc_reg_pct_build pct_bcr;
 	struct arc_reg_cc_build cc_bcr;
-	int i, has_interrupts;
+	int i, has_interrupts, irq;
 	int counter_size;	/* in bits */
 
 	union cc_name {
@@ -637,13 +637,7 @@ static int arc_pmu_device_probe(struct platform_device *pdev)
 		.attr_groups	= arc_pmu->attr_groups,
 	};
 
-	if (has_interrupts) {
-		int irq = platform_get_irq(pdev, 0);
-
-		if (irq < 0) {
-			pr_err("Cannot get IRQ number for the platform\n");
-			return -ENODEV;
-		}
+	if (has_interrupts && (irq = platform_get_irq(pdev, 0) >= 0)) {
 
 		arc_pmu->irq = irq;
 
@@ -652,9 +646,9 @@ static int arc_pmu_device_probe(struct platform_device *pdev)
 				   this_cpu_ptr(&arc_pmu_cpu));
 
 		on_each_cpu(arc_cpu_pmu_irq_init, &irq, 1);
-
-	} else
+	} else {
 		arc_pmu->pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
+	}
 
 	/*
 	 * perf parser doesn't really like '-' symbol in events name, so let's
-- 
2.20.1