[U-Boot] [PATCH v2 1/2] Errata/ARM57: Add basic constructs to handle and apply A57 specific erratas

[York Sun]

On 01/15/2015 11:05 AM, Mark Rutland wrote:
> On Thu, Jan 15, 2015 at 06:10:57AM +0000, bhupesh.sharma at freescale.com wrote:
>> Hi York,
>>
>>> -----Original Message-----
>>> From: Sun York-R58495
>>> Sent: Wednesday, January 14, 2015 9:44 PM
>>> On 01/14/2015 05:46 AM, Bhupesh Sharma wrote:
>>>> This patch adds basic constructs in the ARMv8 u-boot code to handle
>>>> and apply Cortex-A57 specific erratas.
>>>>
>>>> As and example, the framework showcases how erratas 833069, 826974 and
>>>> 828024 can be handled and applied.
>>>>
>>>> Later on this framework can be extended to include other erratas.
>>>>
>>>> Signed-off-by: Bhupesh Sharma <bhupesh.sharma at freescale.com>
>>>> ---
>>>> Changes from v1:
>>>> 	- Addressed York's comment about x29 usage and calling the
>>>> 	  core errata fxup function before the lowlevel_init function
>>>> 	  is called.
>>>>
>>>>  arch/arm/cpu/armv8/start.S   |   51
>>> ++++++++++++++++++++++++++++++++++++++++++
>>>>  arch/arm/include/asm/macro.h |   20 +++++++++++++++++
>>>>  2 files changed, 71 insertions(+)
>>>>
>>>> diff --git a/arch/arm/cpu/armv8/start.S b/arch/arm/cpu/armv8/start.S
>>>> index 4b11aa4..df532f9 100644
>>>> --- a/arch/arm/cpu/armv8/start.S
>>>> +++ b/arch/arm/cpu/armv8/start.S
>>>> @@ -67,6 +67,9 @@ reset:
>>>>  	msr	cpacr_el1, x0			/* Enable FP/SIMD */
>>>>  0:
>>>>
>>>> +	/* Apply ARM core specific erratas */
>>>> +	bl	apply_core_errata
>>>> +
>>>>  	/*
>>>>  	 * Cache/BPB/TLB Invalidate
>>>>  	 * i-cache is invalidated before enabled in icache_enable() @@ -
>>> 97,6
>>>> +100,54 @@ master_cpu:
>>>>
>>>>
>>>> /*--------------------------------------------------------------------
>>>> ---*/
>>>>
>>>> +WEAK(apply_core_errata)
>>>> +
>>>> +	/* For now, we support Cortex-A57 specific errata only */
>>>> +
>>>> +	/* Check if we are running on a Cortex-A57 core */
>>>> +	branch_if_a57_core x0, 1f
>>>> +	b	2f
>>>> +1:
>>>> +	bl	apply_a57_core_errata
>>>> +
>>>> +2:
>>>> +	ret
>>>> +ENDPROC(apply_core_errata)
>>>> +
>>>
>>> Bhupesh,
>>>
>>> Have you tested the new code? I don't think it handles LR correctly. Your
>>> code will be stuck.
>>>
>>
>> Yes, I have tested this on both the LS2085A simulator and emulator platforms.
>> On emulator I tried u-boot boot-to-prompt and on simulator I tried linux boot-to-prompt.
>> Both seem to be working fine.
> 
> Has the apply_a57_core_errata function definitely been called in your
> tests?
> 
> If so the lr should point immediately after it (i.e. at the ret), and so
> the ret should branch to itself, repeatedly.
> 

That's what I thought. I wonder how Bhupesh tested on the simulator.

York