linux-kernel - Re: [PATCH v2 12/15] powerpc/85xx: add time base sync support for e6500

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Message-ID: <20130424112929.GC3172@localhost.localdomain>
Date:	Wed, 24 Apr 2013 19:29:29 +0800
From:	Zhao Chenhui <chenhui.zhao@...escale.com>
To:	Scott Wood <scottwood@...escale.com>
CC:	<linuxppc-dev@...ts.ozlabs.org>, <linux-kernel@...r.kernel.org>,
	<r58472@...escale.com>
Subject: Re: [PATCH v2 12/15] powerpc/85xx: add time base sync support for
 e6500

On Tue, Apr 23, 2013 at 07:04:06PM -0500, Scott Wood wrote:
> On 04/19/2013 05:47:45 AM, Zhao Chenhui wrote:
> >From: Chen-Hui Zhao <chenhui.zhao@...escale.com>
> >
> >For e6500, two threads in one core share one time base. Just need
> >to do time base sync on first thread of one core, and skip it on
> >the other thread.
> >
> >Signed-off-by: Zhao Chenhui <chenhui.zhao@...escale.com>
> >Signed-off-by: Li Yang <leoli@...escale.com>
> >Signed-off-by: Andy Fleming <afleming@...escale.com>
> >---
> > arch/powerpc/platforms/85xx/smp.c |   52
> >+++++++++++++++++++++++++++++++-----
> > 1 files changed, 44 insertions(+), 8 deletions(-)
> >
> >diff --git a/arch/powerpc/platforms/85xx/smp.c
> >b/arch/powerpc/platforms/85xx/smp.c
> >index 74d8cde..5f3eee3 100644
> >--- a/arch/powerpc/platforms/85xx/smp.c
> >+++ b/arch/powerpc/platforms/85xx/smp.c
> >@@ -26,6 +26,7 @@
> > #include <asm/cacheflush.h>
> > #include <asm/dbell.h>
> > #include <asm/fsl_guts.h>
> >+#include <asm/cputhreads.h>
> >
> > #include <sysdev/fsl_soc.h>
> > #include <sysdev/mpic.h>
> >@@ -45,6 +46,7 @@ static u64 timebase;
> > static int tb_req;
> > static int tb_valid;
> > static u32 cur_booting_core;
> >+static bool rcpmv2;
> >
> > #ifdef CONFIG_PPC_E500MC
> > /* get a physical mask of online cores and booting core */
> >@@ -53,26 +55,40 @@ static inline u32 get_phy_cpu_mask(void)
> > 	u32 mask;
> > 	int cpu;
> >
> >-	mask = 1 << cur_booting_core;
> >-	for_each_online_cpu(cpu)
> >-		mask |= 1 << get_hard_smp_processor_id(cpu);
> >+	if (smt_capable()) {
> >+		/* two threads in one core share one time base */
> >+		mask = 1 << cpu_core_index_of_thread(cur_booting_core);
> >+		for_each_online_cpu(cpu)
> >+			mask |= 1 << cpu_core_index_of_thread(
> >+					get_hard_smp_processor_id(cpu));
> >+	} else {
> >+		mask = 1 << cur_booting_core;
> >+		for_each_online_cpu(cpu)
> >+			mask |= 1 << get_hard_smp_processor_id(cpu);
> >+	}
> 
> Where is smt_capable defined()?  I assume somewhere in the patchset
> but it's a pain to search 12 patches...
> 

It is defined in arch/powerpc/include/asm/topology.h.
	#define smt_capable()           (cpu_has_feature(CPU_FTR_SMT))

Thanks for your review again.

> Is this really about whether we're SMT-capable or whether we have
> rcpm v2?
> 
> -Scott

I think this "if" statement can be removed. The cpu_core_index_of_thread()
can return the correct cpu number with thread or without thread.

Like this:
static inline u32 get_phy_cpu_mask(void)
{
	u32 mask;
	int cpu;

	mask = 1 << cpu_core_index_of_thread(cur_booting_core);
	for_each_online_cpu(cpu)
		mask |= 1 << cpu_core_index_of_thread(
				get_hard_smp_processor_id(cpu));

	return mask;
}

-Chenhui

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