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SubjectRe: [PATCH] socfpga_a10: reset CPU1 in socfpga_cpu_kill()

On 2017年05月12日 22:36, Mark Rutland wrote:
> On Wed, May 10, 2017 at 01:13:04AM -0400, yanjiang.jin@windriver.com wrote:
>> From: Yanjiang Jin <yanjiang.jin@windriver.com>
>>
>> Kexec's second kernel would hang if CPU1 isn't reset.
>>
>> Signed-off-by: Yanjiang Jin <yanjiang.jin@windriver.com>
>> ---
>> arch/arm/mach-socfpga/platsmp.c | 12 +++++++++++-
>> 1 file changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/mach-socfpga/platsmp.c b/arch/arm/mach-socfpga/platsmp.c
>> index 0ee7677..db3940e 100644
>> --- a/arch/arm/mach-socfpga/platsmp.c
>> +++ b/arch/arm/mach-socfpga/platsmp.c
>> @@ -117,6 +117,16 @@ static int socfpga_cpu_kill(unsigned int cpu)
>> {
>> return 1;
>> }
>> +
>> +static int socfpga_a10_cpu_kill(unsigned int cpu)
>> +{
>> + /* This will put CPU #1 into reset. */
>> + if (socfpga_cpu1start_addr)
>> + writel(RSTMGR_MPUMODRST_CPU1, rst_manager_base_addr +
>> + SOCFPGA_A10_RSTMGR_MODMPURST);
>> +
>> + return 1;
>> +}
>> #endif
> I agree that currently, socfpga_cpu_die is completely bogus, as the CPU is just
> sat in WFI with the MMU, caches, etc enabled, and not actually off:
>
> static void socfpga_cpu_die(unsigned int cpu)
> {
> /* Do WFI. If we wake up early, go back into WFI */
> while (1)
> cpu_do_idle();
> }
>
> ... so that goes wrong as soon as the kerenl text gets ovewritten.
>
> However, AFAICT, this patch forcibly resets is without any teardown
> having happened. That will surely result in data being lost from the
> caches, for example.
>
> So I think this is incomplete.
Hi Mark,

I think I got what you mean. So far, flush_cache is the only thing that
I can think of.
Can we just add flush_cache_all in cpu_die() now, and add other missing
parts(if have) in the future.

Thanks!
Yanjiang

> Thanks,
> Mark.
>
>>
>> static const struct smp_operations socfpga_smp_ops __initconst = {
>> @@ -133,7 +143,7 @@ static int socfpga_cpu_kill(unsigned int cpu)
>> .smp_boot_secondary = socfpga_a10_boot_secondary,
>> #ifdef CONFIG_HOTPLUG_CPU
>> .cpu_die = socfpga_cpu_die,
>> - .cpu_kill = socfpga_cpu_kill,
>> + .cpu_kill = socfpga_a10_cpu_kill,
>> #endif
>> };
>>
>> --
>> 1.9.1
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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