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

[Ziyuan Xu]

Hi Tom,


On 2016年07月29日 09:12, Tom Rini wrote:
> On Fri, Jul 29, 2016 at 09:06:29AM +0800, Ziyuan Xu wrote:
>> 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?:-)
> I would really like to try and fix the other possibly latent issues that
> we have by not calling a real ISB.  Please try moving towards all places
> that need an isb calling the correct one from barriers.h and giving it a
> spin on the hardware you have available.
I used ISB instead of isb(), everything works sane on my rockchip rk3288 
boards.:-)
Will you send a patch to fix it and other possibly latent issues? Or 
apply this temporarily?

>