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

[Matt Porter]

On Thu, Mar 05, 2015 at 11:56:54AM -0600, 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?

Correct. My 3530 beagle is r1p3 and your xM is r3p2.

> Did i get the code wrong here? Need some additional eyes here :(

I verified by inspection that your code below is fine but I also shoved
it into a command line app with some doctored r1 content and confirmed
that it really does work for the r3p2 case. So I'm not yet clear as
to why it's engaging the erratum fix for r3p2.

-Matt

> 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
> 
> 
> -- 
> Regards,
> Nishanth Menon
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