[PATCH v8 2/2] arm-soc: Add support for arm-based tango4 platforms

santosh shilimkar santosh.shilimkar at oracle.com
Mon Nov 2 10:37:40 PST 2015

On 11/2/2015 10:26 AM, Mark Rutland wrote:
>>> +ENTRY(tango_smc)
>>> +	push	{lr}
>>> +	mov	ip, r1
>>> +	dsb
>> Did you ever get a straight answer on the dsb here?
> We didn't. Having a look just now, the earliest example appears to be
> in OMAP4 L2 support patches back in 2009 [1]. I was not able to find a
> rationale.
> Given that the MMU is on (and speculative accesses are permitted) I
> can't see what the DSB achieves -- it can't quiesce the memory system.
> Santosh, any idea?
IIRC, it was requirement from the OMAP ROM code to have a dsb before
we call the SMC routine. I can't recollect more than that now.


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