Date: Wed, 5 Aug 2015 19:08:26 +0800
From: Chenhui Zhao <chenhui.zhao@freescale.com>
Subject: Re: [PATCH 3/3] PowerPC/mpc85xx: Add hotplug support on E6500 cores
To: Scott Wood <scottwood@freescale.com>
CC: <b29983@freescale.com>, <b07421@freescale.com>,
        <linux-kernel@vger.kernel.org>,
        Tang Yuantian <Yuantian.Tang@freescale.com>,
        Tang Yuantian <Yuantian.Tang@feescale.com>
Message-ID: <1438772906.21522.2@remotesmtp.freescale.net>
In-Reply-To: <1438388531.19345.88.camel@freescale.com>
References: <1438334444-31919-1-git-send-email-b29983@freescale.com>
	<1438334444-31919-3-git-send-email-b29983@freescale.com>
	<1438388531.19345.88.camel@freescale.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"; format=flowed
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Aug 2015 11:08:29.7299
 (UTC)
X-MS-Exchange-CrossTenant-Id: 710a03f5-10f6-4d38-9ff4-a80b81da590d
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=710a03f5-10f6-4d38-9ff4-a80b81da590d;Ip=[192.88.158.2];Helo=[az84smr01.freescale.net]
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM2PR03MB573
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 3029
Lines: 93


On Sat, Aug 1, 2015 at 8:22 AM, Scott Wood <scottwood@freescale.com> 
wrote:
> On Fri, 2015-07-31 at 17:20 +0800, b29983@freescale.com wrote:
>>  diff --git a/arch/powerpc/platforms/85xx/smp.c
>>  b/arch/powerpc/platforms/85xx/smp.c
>>  index 7f0dadb..8652a49 100644
>>  --- a/arch/powerpc/platforms/85xx/smp.c
>>  +++ b/arch/powerpc/platforms/85xx/smp.c
>>  @@ -189,15 +189,22 @@ static inline u32 read_spin_table_addr_l(void
>>  *spin_table)
>>   static void wake_hw_thread(void *info)
>>   {
>>        void fsl_secondary_thread_init(void);
>>  -     unsigned long imsr1, inia1;
>>  +     unsigned long imsr, inia;
>>        int nr = *(const int *)info;
>>  -
>>  -     imsr1 = MSR_KERNEL;
>>  -     inia1 = *(unsigned long *)fsl_secondary_thread_init;
>>  -
>>  -     mttmr(TMRN_IMSR1, imsr1);
>>  -     mttmr(TMRN_INIA1, inia1);
>>  -     mtspr(SPRN_TENS, TEN_THREAD(1));
>>  +     int hw_cpu = get_hard_smp_processor_id(nr);
>>  +     int thread_idx = cpu_thread_in_core(hw_cpu);
>>  +
>>  +     booting_cpu_hwid = (u32)hw_cpu;
> 
> Unnecessary cast.  Please explain why you need booting_cpu_hwid.
> 
> 
>>  +     imsr = MSR_KERNEL;
>>  +     inia = *(unsigned long *)fsl_secondary_thread_init;
>>  +     if (thread_idx == 0) {
>>  +             mttmr(TMRN_IMSR0, imsr);
>>  +             mttmr(TMRN_INIA0, inia);
>>  +     } else {
>>  +             mttmr(TMRN_IMSR1, imsr);
>>  +             mttmr(TMRN_INIA1, inia);
>>  +     }
>>  +     mtspr(SPRN_TENS, TEN_THREAD(thread_idx));
> 
> Please rebase this on top of http://patchwork.ozlabs.org/patch/496952/

OK.

> 
> 
>>  +             /*
>>  +              * If both threads are offline, reset core to start.
>>  +              * When core is up, Thread 0 always gets up first,
>>  +              * so bind the current logical cpu with Thread 0.
>>  +              */
>>  +             if (hw_cpu != cpu_first_thread_sibling(hw_cpu)) {
>>  +                     int hw_cpu1, hw_cpu2;
>>  +
>>  +                     hw_cpu1 = get_hard_smp_processor_id(primary);
>>  +                     hw_cpu2 = get_hard_smp_processor_id(primary + 
>> 1);
>>  +                     set_hard_smp_processor_id(primary, hw_cpu2);
>>  +                     set_hard_smp_processor_id(primary + 1, 
>> hw_cpu1);
>>  +                     /* get new physical cpu id */
>>  +                     hw_cpu = get_hard_smp_processor_id(nr);
> 
> NACK as discussed in http://patchwork.ozlabs.org/patch/454944/
> 
> -Scott

You said,

    There's no need for this. I have booting from a thread1, and having 
it
    kick its thread0, working locally without messing with the hwid/cpu
    mapping.

I still have questions here. After a core reset, how can you boot 
Thread1
of the core first. As I know, Thread0 boots up first by default.

-Chenhui


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/