linux-kernel - [RFC PATCH v1 5/9] MIPS: Remove perf

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Date:   Thu, 7 Sep 2017 16:25:38 -0700
From:   Paul Burton <paul.burton@...tec.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ralf Baechle <ralf@...ux-mips.org>
CC:     <dianders@...omium.org>, James Hogan <james.hogan@...tec.com>,
        Brian Norris <briannorris@...omium.org>,
        Jason Cooper <jason@...edaemon.net>,
        <jeffy.chen@...k-chips.com>, Marc Zyngier <marc.zyngier@....com>,
        <linux-kernel@...r.kernel.org>, <linux-mips@...ux-mips.org>,
        <tfiga@...omium.org>, Paul Burton <paul.burton@...tec.com>
Subject: [RFC PATCH v1 5/9] MIPS: Remove perf_irq

Remove the perf_irq function pointer which we no longer use. The
cevt-r4k clock event driver no longer needs to call it, which simplifies
c0_compare_interrupt(), and we drop its definition & declarations.

Signed-off-by: Paul Burton <paul.burton@...tec.com>
Cc: James Hogan <james.hogan@...tec.com>
Cc: Jason Cooper <jason@...edaemon.net>
Cc: Marc Zyngier <marc.zyngier@....com>
Cc: Ralf Baechle <ralf@...ux-mips.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-kernel@...r.kernel.org
Cc: linux-mips@...ux-mips.org
---

 arch/mips/include/asm/time.h |  1 -
 arch/mips/kernel/cevt-r4k.c  | 48 +++++++++-----------------------------------
 arch/mips/kernel/time.c      |  9 ---------
 arch/mips/oprofile/op_impl.h |  2 --
 4 files changed, 10 insertions(+), 50 deletions(-)

diff --git a/arch/mips/include/asm/time.h b/arch/mips/include/asm/time.h
index 17d4cd20f18c..7a21792826a6 100644
--- a/arch/mips/include/asm/time.h
+++ b/arch/mips/include/asm/time.h
@@ -45,7 +45,6 @@ extern unsigned int mips_hpt_frequency;
  * The performance counter IRQ on MIPS is a close relative to the timer IRQ
  * so it lives here.
  */
-extern int (*perf_irq)(void);
 extern int __weak get_c0_perfcount_int(void);
 
 /*
diff --git a/arch/mips/kernel/cevt-r4k.c b/arch/mips/kernel/cevt-r4k.c
index dd6a18bc10ab..893aa32759d9 100644
--- a/arch/mips/kernel/cevt-r4k.c
+++ b/arch/mips/kernel/cevt-r4k.c
@@ -108,54 +108,26 @@ static unsigned int calculate_min_delta(void)
 DEFINE_PER_CPU(struct clock_event_device, mips_clockevent_device);
 int cp0_timer_irq_installed;
 
-/*
- * Possibly handle a performance counter interrupt.
- * Return true if the timer interrupt should not be checked
- */
-static inline int handle_perf_irq(int r2)
-{
-	/*
-	 * The performance counter overflow interrupt may be shared with the
-	 * timer interrupt (cp0_perfcount_irq < 0). If it is and a
-	 * performance counter has overflowed (perf_irq() == IRQ_HANDLED)
-	 * and we can't reliably determine if a counter interrupt has also
-	 * happened (!r2) then don't check for a timer interrupt.
-	 */
-	return (cp0_perfcount_irq < 0) &&
-		perf_irq() == IRQ_HANDLED &&
-		!r2;
-}
-
 irqreturn_t c0_compare_interrupt(int irq, void *dev_id)
 {
-	const int r2 = cpu_has_mips_r2_r6;
 	struct clock_event_device *cd;
 	int cpu = smp_processor_id();
 
 	/*
-	 * Suckage alert:
-	 * Before R2 of the architecture there was no way to see if a
-	 * performance counter interrupt was pending, so we have to run
-	 * the performance counter interrupt handler anyway.
+	 * If we have the Cause.TI bit with which to decode whether this was in
+	 * fact a timer interrupt, rather than another which shares the CPU
+	 * pin, then check that & return if no timer interrupt is pending.
 	 */
-	if (handle_perf_irq(r2))
-		return IRQ_HANDLED;
+	if (cpu_has_mips_r2_r6 && !(read_c0_cause() & CAUSEF_TI))
+		return IRQ_NONE;
 
-	/*
-	 * The same applies to performance counter interrupts.	But with the
-	 * above we now know that the reason we got here must be a timer
-	 * interrupt.  Being the paranoiacs we are we check anyway.
-	 */
-	if (!r2 || (read_c0_cause() & CAUSEF_TI)) {
-		/* Clear Count/Compare Interrupt */
-		write_c0_compare(read_c0_compare());
-		cd = &per_cpu(mips_clockevent_device, cpu);
-		cd->event_handler(cd);
+	/* Clear Count/Compare Interrupt */
+	write_c0_compare(read_c0_compare());
 
-		return IRQ_HANDLED;
-	}
+	cd = &per_cpu(mips_clockevent_device, cpu);
+	cd->event_handler(cd);
 
-	return IRQ_NONE;
+	return IRQ_HANDLED;
 }
 
 struct irqaction c0_compare_irqaction = {
diff --git a/arch/mips/kernel/time.c b/arch/mips/kernel/time.c
index a6ebc8135112..1090d1c11afa 100644
--- a/arch/mips/kernel/time.c
+++ b/arch/mips/kernel/time.c
@@ -49,15 +49,6 @@ int update_persistent_clock(struct timespec now)
 	return rtc_mips_set_mmss(now.tv_sec);
 }
 
-static int null_perf_irq(void)
-{
-	return 0;
-}
-
-int (*perf_irq)(void) = null_perf_irq;
-
-EXPORT_SYMBOL(perf_irq);
-
 /*
  * time_init() - it does the following things.
  *
diff --git a/arch/mips/oprofile/op_impl.h b/arch/mips/oprofile/op_impl.h
index a4e758a39af4..9b0b295bdaf1 100644
--- a/arch/mips/oprofile/op_impl.h
+++ b/arch/mips/oprofile/op_impl.h
@@ -10,8 +10,6 @@
 #ifndef OP_IMPL_H
 #define OP_IMPL_H 1
 
-extern int (*perf_irq)(void);
-
 /* Per-counter configuration as set via oprofilefs.  */
 struct op_counter_config {
 	unsigned long enabled;
-- 
2.14.1