[U-Boot] [linux-sunxi] Re: [PATCH 02/12] sunxi: simplify ACTLR.SMP bit set #ifdef

[André Przywara]

On 13/01/17 08:09, Vishnu Patekar wrote:
Hi Vishnu,

> Even for the single core cortex-a7, SMP bit should be set before
> enabling MMU and cache.
> 
> Reference: Cortex A7 r0p5 TRM. section 4.3.31.

Ah, good point, thanks for the heads up. I was misled by the SMP name
when answering Icenowy.
So it's about coherency in general and we need the bit for TLBs and
caches to work as well.
Let me check what that means for the other SoCs and whether we need to
rename the config symbol then.

Cheers,
Andre.

> 
> On Fri, Jan 13, 2017 at 12:41 PM, Icenowy Zheng <icenowy at aosc.xyz> wrote:
>>
>>
>> 13.01.2017, 09:34, "Andre Przywara" <andre.przywara at arm.com>:
>>> Instead of enumerating all SoC families that need that bit set, let's
>>> just express this more clearly: The SMP bits needs to be set on
>>> SMP capable ARMv7 CPUs. It's much easier to Kconfig to express it the
>>> other way round, so we use ! NO_SMP and ! ARM64.
>>
>> How about single-core Cortex-A7?
>>
>>>
>>> Signed-off-by: Andre Przywara <andre.przywara at arm.com>
>>> ---
>>>  arch/arm/mach-sunxi/board.c | 5 +----
>>>  board/sunxi/Kconfig | 6 ++++++
>>>  2 files changed, 7 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/arch/arm/mach-sunxi/board.c b/arch/arm/mach-sunxi/board.c
>>> index 58fbacb..5a63124 100644
>>> --- a/arch/arm/mach-sunxi/board.c
>>> +++ b/arch/arm/mach-sunxi/board.c
>>> @@ -180,10 +180,7 @@ void s_init(void)
>>>          /* No H3 BSP, boot0 seems to not modify SUNXI_SRAMC_BASE + 0x44 */
>>>  #endif
>>>
>>> -#if defined CONFIG_MACH_SUN6I || \
>>> - defined CONFIG_MACH_SUN7I || \
>>> - defined CONFIG_MACH_SUN8I || \
>>> - defined CONFIG_MACH_SUN9I
>>> +#if !defined(CONFIG_SUNXI_NO_SMP) && !defined(CONFIG_ARM64)
>>>          /* Enable SMP mode for CPU0, by setting bit 6 of Auxiliary Ctl reg */
>>>          asm volatile(
>>>                  "mrc p15, 0, r0, c1, c0, 1\n"
>>> diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig
>>> index 37b4252..79b6fa7 100644
>>> --- a/board/sunxi/Kconfig
>>> +++ b/board/sunxi/Kconfig
>>> @@ -27,6 +27,10 @@ config SPL_POWER_SUPPORT
>>>  config SPL_SERIAL_SUPPORT
>>>          default y
>>>
>>> +config SUNXI_NO_SMP
>>> + bool
>>> + default n
>>> +
>>>  # Note only one of these may be selected at a time! But hidden choices are
>>>  # not supported by Kconfig
>>>  config SUNXI_GEN_SUN4I
>>> @@ -50,12 +54,14 @@ choice
>>>  config MACH_SUN4I
>>>          bool "sun4i (Allwinner A10)"
>>>          select CPU_V7
>>> + select SUNXI_NO_SMP
>>>          select SUNXI_GEN_SUN4I
>>>          select SUPPORT_SPL
>>>
>>>  config MACH_SUN5I
>>>          bool "sun5i (Allwinner A13)"
>>>          select CPU_V7
>>> + select SUNXI_NO_SMP
>>>          select SUNXI_GEN_SUN4I
>>>          select SUPPORT_SPL
>>>
>>> --
>>> 2.8.2
>>
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