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

[Mark Rutland]

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.

Mark.