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Subject[PATCH] ARM: owl: smp: Drop bogus holding pen
Date
The S500 SoC can start secondary CPUs without busy-looping for pen_release,
so simplify the SMP code compared to the LeMaker kernel tree.

Fixes: 172067e0bc87 ("ARM: owl: Implement CPU enable-method for S500")
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Cc: David Liu <liuwei@actions-semi.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
---
arch/arm/mach-actions/headsmp.S | 20 ++------------------
arch/arm/mach-actions/platsmp.c | 29 +----------------------------
2 files changed, 3 insertions(+), 46 deletions(-)

diff --git a/arch/arm/mach-actions/headsmp.S b/arch/arm/mach-actions/headsmp.S
index dc4832fc101a..65f53bdb69e7 100644
--- a/arch/arm/mach-actions/headsmp.S
+++ b/arch/arm/mach-actions/headsmp.S
@@ -2,6 +2,8 @@
* Copyright 2012 Actions Semi Inc.
* Author: Actions Semi, Inc.
*
+ * Copyright (c) 2017 Andreas Färber
+ *
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
@@ -46,23 +48,5 @@ ENTRY(owl_v7_invalidate_l1)
ENDPROC(owl_v7_invalidate_l1)

ENTRY(owl_secondary_startup)
- mrc p15, 0, r0, c0, c0, 5
- and r0, r0, #0xf
- adr r4, 1f
- ldmia r4, {r5, r6}
- sub r4, r4, r5
- add r6, r6, r4
-pen:
- ldr r7, [r6]
- cmp r7, r0
- bne pen
-
- /*
- * we've been released from the holding pen: secondary_stack
- * should now contain the SVC stack for this core
- */
bl owl_v7_invalidate_l1
b secondary_startup
-
-1: .long .
- .long pen_release
diff --git a/arch/arm/mach-actions/platsmp.c b/arch/arm/mach-actions/platsmp.c
index b4806ce0e9bb..12a9e331b432 100644
--- a/arch/arm/mach-actions/platsmp.c
+++ b/arch/arm/mach-actions/platsmp.c
@@ -41,26 +41,6 @@ static int ncores;

static DEFINE_SPINLOCK(boot_lock);

-static void write_pen_release(int val)
-{
- pen_release = val;
- smp_wmb();
- __cpuc_flush_dcache_area((void *)&pen_release, sizeof(pen_release));
- outer_clean_range(__pa(&pen_release), __pa(&pen_release + 1));
-}
-
-static void s500_smp_secondary_init(unsigned int cpu)
-{
- /*
- * let the primary processor know we're out of the
- * pen, then head off into the C entry point
- */
- write_pen_release(-1);
-
- spin_lock(&boot_lock);
- spin_unlock(&boot_lock);
-}
-
void owl_secondary_startup(void);

static int s500_wakeup_secondary(unsigned int cpu)
@@ -115,12 +95,6 @@ static int s500_smp_boot_secondary(unsigned int cpu, struct task_struct *idle)

spin_lock(&boot_lock);

- /*
- * The secondary processor is waiting to be released from
- * the holding pen - release it, then wait for it to flag
- * that it has been released by resetting pen_release.
- */
- write_pen_release(cpu_logical_map(cpu));
smp_send_reschedule(cpu);

timeout = jiffies + (1 * HZ);
@@ -134,7 +108,7 @@ static int s500_smp_boot_secondary(unsigned int cpu, struct task_struct *idle)

spin_unlock(&boot_lock);

- return pen_release != -1 ? -ENOSYS : 0;
+ return 0;
}

static void __init s500_smp_prepare_cpus(unsigned int max_cpus)
@@ -192,7 +166,6 @@ static void __init s500_smp_prepare_cpus(unsigned int max_cpus)

static const struct smp_operations s500_smp_ops __initconst = {
.smp_prepare_cpus = s500_smp_prepare_cpus,
- .smp_secondary_init = s500_smp_secondary_init,
.smp_boot_secondary = s500_smp_boot_secondary,
};
CPU_METHOD_OF_DECLARE(s500_smp, "actions,s500-smp", &s500_smp_ops);
--
2.12.3
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