[U-Boot] [PATCH] arm: re-implement proper ISB instruction for ARMv7-A

[Ziyuan Xu]

Hi Tom,

On 2016年07月29日 08:34, Tom Rini wrote:
> On Fri, Jul 29, 2016 at 07:34:09AM +0800, Ziyuan Xu wrote:
>> Hi Tom,
>>
>> On 2016年07月29日 06:15, Tom Rini wrote:
>>> On Thu, Jul 28, 2016 at 07:03:17PM +0800, Chen-Yu Tsai wrote:
>>>> Hi,
>>>>
>>>> On Thu, Jul 28, 2016 at 6:13 PM, Ziyuan Xu <xzy.xu at rock-chips.com> wrote:
>>>>> For ARMv7-A architecture, the valid ISB instruction is asm volatile("isb").
>>>>>
>>>>> This patch fixes the U-Boot was stuck in invalidate_dcache_all() before
>>>>> booting linux kernel, which occurred on rk3288-base development board
>>>>> such as evb-rk3288, rock2-rk3288. And something output via console like:
>>>>>
>>>>> => bootz 0x2000000
>>>>> 0x02000000
>>>>>     ramdisk start = 0x00000000, ramdisk end = 0x00000000
>>>>>     Continuing to boot without FDT
>>>>>     Initial value for argc=3
>>>>>     Final value for argc=3
>>>>>     using: ATAGS
>>>>>
>>>>>     Starting kernel ...
>>>>>
>>>>> Linux kernel exactly the same way(see arch/arm/include/asm/barrier.h).
>>>>>
>>>>> Signed-off-by: Ziyuan Xu <xzy.xu at rock-chips.com>
>>>>> ---
>>>>>
>>>>>   arch/arm/include/asm/system.h | 6 ++++--
>>>>>   1 file changed, 4 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h
>>>>> index 2bdc0be..12d4ba0 100644
>>>>> --- a/arch/arm/include/asm/system.h
>>>>> +++ b/arch/arm/include/asm/system.h
>>>>> @@ -227,13 +227,15 @@ void __noreturn psci_system_reset(bool smc);
>>>>>    */
>>>>>   void save_boot_params_ret(void);
>>>>>
>>>>> -#define isb() __asm__ __volatile__ ("" : : : "memory")
>>>>> -
>>>>>   #define nop() __asm__ __volatile__("mov\tr0,r0\t@ nop\n\t");
>>>>>
>>>>>   #ifdef __ARM_ARCH_7A__
>>>>> +#define isb() __asm__ __volatile__ ("isb" : : : "memory")
>>>>> +
>>>>>   #define wfi() __asm__ __volatile__ ("wfi" : : : "memory")
>>>>>   #else
>>>>> +#define isb() __asm__ __volatile__ ("" : : : "memory")
>>>>> +
>>>>>   #define wfi()
>>>>>   #endif
>>>>>
>>>> arch/arm/include/asm/barriers.h already has a proper set of
>>>> ISB/DSB macros. Please consider using those instead.
>>> Please fix arch/arm/include/asm/system.h to use the macros found in
>>> barriers.h rather than have their own versions.  Thanks!
>> If I understand correctly, I can change into as bellow:
>> #define isb() ISB
>> How about it?
> Well, I'd rather not have ISB and isb, just ISB, which means we might
> have to fix other places too.  If that starts looking too huge, we can
> do this in steps and just do what you suggested for now and for next
> release move everything over.
As I mentioned before, arch/arm/include/asm/barriers.h defined ISB 
macro.  If I only want to fix the issue which I hit on rk3288 board, I 
just use ISB in arch/arm/include/asm/system.h::set_cr() instead of 
isb(). But isb() had been invoked in some places.

I can't verify integrallty after all revision, it involve some boards 
and feature. But this does fix for rk3288, if you agree with me, could 
you apply it provisionally?:-)

>