[U-Boot] [PATCH V4 00/11] ARM: OMAP3-DRA7: CP15 erratum workarounds and improvements

[Nishanth Menon]

On 03/05/2015 11:56 AM, Nishanth Menon wrote:
> On 03/05/2015 10:21 AM, Matt Porter wrote:
>> On Tue, Mar 03, 2015 at 04:26:17PM -0600, Nishanth Menon wrote:
>>> The fourth incarnation of this series to address review comments on V3
>>>
>>> With all the usual disclaimers and request to see V1 of the series for a
>>> detailed blurb.. As usual additional testing preferred.. Sorry, I dont have
>>> access to all possible variants atm..
>>>
>>> changes since v3:
>>> 	- few corrections - i have tried to do a push-pop of register params.
>>> 	  hopefully, they should do the job
>>> 	- smc with a makefile handling of secure-ext enablement.. (stolen from kernel).
>>>
>>> V3: http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/213207/focus=213307
>>> V2: http://comments.gmane.org/gmane.comp.boot-loaders.u-boot/213060
>>> V1: http://comments.gmane.org/gmane.comp.boot-loaders.u-boot/212174
>>>
>>> Testing: with http://paste.ubuntu.org.cn/2522971 (4.0-rc1 patch)
>>>
>>> BeagleBoard-X15: http://pastebin.ubuntu.com/10518934/
>>> 	Before: CPUID=0x412fc0f2 L2CTLR=0x01800083 L2ACLR=0x00000000 L2PFR=0x000009b0 ACTLR=0x00000040
>>> 	After: CPUID=0x412fc0f2 L2CTLR=0x01800083 L2ACLR=0x00000198 L2PFR=0x000009b0 ACTLR=0x00000040
>>>
>>> OMAP5uEVM: http://pastebin.ubuntu.com/10518958/
>>> 	Before: CPUID=0x412fc0f2 L2CTLR=0x01800083 L2ACLR=0x00000000 L2PFR=0x000009b0 ACTLR=0x00000040
>>> 	After: CPUID=0x412fc0f2 L2CTLR=0x01800083 L2ACLR=0x00000198 L2PFR=0x000009b0 ACTLR=0x00000040
>>>
>>> Beagle-XM: http://pastebin.ubuntu.com/10519417/ (this is a r2p3 device)
>>> 	Before: CPUID=0x413fc082 ACR=0x000000e2 L2AUXCR=0x00000042
>>> 	After: CPUID=0x413fc082 ACR=0x00000042 L2AUXCR=0x00000042
>>
>> I also got the same results on a Beagle-XM Rev. C1
>>  
>>> I dont have access to other omap3 platforms to give a better coverage
>>
>> Beagle Rev. C2 (OMAP3530): http://pastebin.com/f5JcvRf4 
>> 	Before: CPUID=0x411fc083 ACR=0x000000e2 L2AUXCR=0x00000042
>> 	After: CPUID=0x411fc083 ACR=0x00000042 L2AUXCR=0x00000042
>>
>> Tested-by: Matt Porter <mporter at konsulko.com>
> 
> Thanks for testing.
> 
>> [With build workaround I noted elsewhere in the thread]
>>
> that should have been a r1p3 device(needs errata), right and mine
> should really be a r3p2?
> 
> Did i get the code wrong here? Need some additional eyes here :(
> 
> http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0432c/Bhccjgga.html
> 
> mrc p15, 0, r1, c0, c0, 0       @ r1 has Read Main ID Register (MIDR)
> mov r3, r1, lsr #20             @ get variant field
> and r3, r3, #0xf                @ r3 has CPU variant
> and r4, r1, #0xf                @ r4 has CPU revision
> 
> mov r2, r3, lsl #4              @ shift variant field for combined value
> orr r2, r4, r2                  @ r2 has combined CPU variant + revision
> 
>          cmp     r2, #0x21               @ Only on < r2p1
>          bge     skip_errata_621766
> 
> 

Alright, thanks to Jtag debugger and replaced 'bgt skip_errata' with
'blt skip_errata (forcing errata flow on my "non-errata beagleboard-xm
board") found the issue. (A bit embarrassed to be staring at it and
not recollecting)..

I should have s/b v7_arch_cp15_set_acr/bl v7_arch_cp15_set_acr/

Since I was not branching and linking (just branching), I was
returning back to the caller of cpu_init_cp15 when the call from
v7_arch_cp15_set_acr was returning, instead of returning back to
v7_arch_cp15_set_acr! elementary error! Sorry, did not see it
previously with A15 erratum since it was a single one to walk down and
follow on errata never took place.

Please standby for a v5 with proper code flow. Apologies on requesting
testing again..

-- 
Uggh... very very embarrassedely yours,
Nishanth Menon