[PATCH 14/17] ARM: mvebu: synchronize secondary CPU clocks on resume
From: Thomas Petazzoni <hidden>
Date: 2014-10-24 11:59:27
Also in:
linux-arm-kernel
Subsystem:
arm port, arm/marvell kirkwood and armada 370, 375, 38x, 39x, xp, 3700, 7k/8k, cn9130 soc support, the rest · Maintainers:
Russell King, Andrew Lunn, Gregory Clement, Sebastian Hesselbarth, Linus Torvalds
Possibly related (same subject, not in this thread)
- 2014-11-10 · Re: [PATCH 14/17] ARM: mvebu: synchronize secondary CPU clocks on resume · Gregory CLEMENT <hidden>
The Armada XP has multiple cores clocked by independent clocks. The SMP startup code contains a function called set_secondary_cpus_clock() called in armada_xp_smp_prepare_cpus() to ensure the clocks of the secondary CPUs match the clock of the boot CPU. With the introduction of suspend/resume, this operation is no longer needed when booting the system, but also when existing the suspend to RAM state. Therefore this commit reworks a bit the logic: instead of configuring the clock of all secondary CPUs in armada_xp_smp_prepare_cpus(), we do it on a per-secondary CPU basis in armada_xp_boot_secondary(), as this function gets called when existing suspend to RAM for each secondary CPU. Since the function now only takes care of one CPU, we rename it from set_secondary_cpus_clock() to set_secondary_cpu_clock(), and it looses its __init marker, as it is now used beyond the system initialization. Note that we can't use smp_processor_id() directly, because when exiting from suspend to RAM, the code is apparently executed with preemption enabled, so smp_processor_id() is not happy (prints a warning). We therefore switch to using get_cpu()/put_cpu(), even though we pretty much have the guarantee that the code starting the secondary CPUs is going to run on the boot CPU and will not be migrated. Signed-off-by: Thomas Petazzoni <thomas.petazzoni-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> --- arch/arm/mach-mvebu/platsmp.c | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-)
diff --git a/arch/arm/mach-mvebu/platsmp.c b/arch/arm/mach-mvebu/platsmp.c
index 895dc37..e65e69a 100644
--- a/arch/arm/mach-mvebu/platsmp.c
+++ b/arch/arm/mach-mvebu/platsmp.c@@ -33,7 +33,7 @@ #define AXP_BOOTROM_BASE 0xfff00000 #define AXP_BOOTROM_SIZE 0x100000 -static struct clk *__init get_cpu_clk(int cpu) +static struct clk *get_cpu_clk(int cpu) { struct clk *cpu_clk; struct device_node *np = of_get_cpu_node(cpu, NULL);
@@ -46,29 +46,28 @@ static struct clk *__init get_cpu_clk(int cpu) return cpu_clk; } -static void __init set_secondary_cpus_clock(void) +static void set_secondary_cpu_clock(unsigned int cpu) { - int thiscpu, cpu; + int thiscpu; unsigned long rate; struct clk *cpu_clk; - thiscpu = smp_processor_id(); + thiscpu = get_cpu(); + cpu_clk = get_cpu_clk(thiscpu); if (!cpu_clk) - return; + goto out; clk_prepare_enable(cpu_clk); rate = clk_get_rate(cpu_clk); - /* set all the other CPU clk to the same rate than the boot CPU */ - for_each_possible_cpu(cpu) { - if (cpu == thiscpu) - continue; - cpu_clk = get_cpu_clk(cpu); - if (!cpu_clk) - return; - clk_set_rate(cpu_clk, rate); - clk_prepare_enable(cpu_clk); - } + cpu_clk = get_cpu_clk(cpu); + if (!cpu_clk) + goto out; + clk_set_rate(cpu_clk, rate); + clk_prepare_enable(cpu_clk); + +out: + put_cpu(); } static int armada_xp_boot_secondary(unsigned int cpu, struct task_struct *idle)
@@ -78,6 +77,7 @@ static int armada_xp_boot_secondary(unsigned int cpu, struct task_struct *idle) pr_info("Booting CPU %d\n", cpu); hw_cpu = cpu_logical_map(cpu); + set_secondary_cpu_clock(hw_cpu); mvebu_pmsu_set_cpu_boot_addr(hw_cpu, armada_xp_secondary_startup); /*
@@ -126,7 +126,6 @@ static void __init armada_xp_smp_prepare_cpus(unsigned int max_cpus) struct resource res; int err; - set_secondary_cpus_clock(); flush_cache_all(); set_cpu_coherent();
--
2.0.0
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