[U-Boot] [PATCH] OMAP3: workaround for ARM Cortex-A8 erratum 725233

[Måns Rullgård]

Siarhei Siamashka <siarhei.siamashka at gmail.com> writes:

> On Sunday 07 February 2010, Tom wrote:
>> Siarhei Siamashka wrote:
>> > 725233: PLD instructions executed with PLD data forwarding
>> > enabled can result in a processor deadlock
>> >
>> > Signed-off-by: Siarhei Siamashka <siarhei.siamashka at gmail.com>
>>
>> Please add a detailed comment on the errata.
>
> The short summary is pretty much complete (PLD data forwarding is not working
> correctly and needs to be turned off to prevent problems). Though it really
> makes sense to add that:
> 1. only r1pX revisions of Cortex-A8 are affected
> 2. performance impact is practically non-existant
>
> The detailed description of this erratum is available in the official
> Cortex-A8 errata list. I'm not sure about directly copying full erratum
> description text here. Anyway, this workaround would be better submitted
> by somebody TI. I'm just "guilty" of triggering this deadlock with some
> ARM NEON optimizations from pixman library, so feel a bit of responsibility
> for it too.
>
>> Also looks like this jumping to ROM code.
>> Can this be done without a ROM code call ?
>
> I just added it to the part of code which is already doing similar things
> (sets L1NEON and other bits from AUXCR with some icky looking assembly via
> ROM code call). Most likely it can be also done in some other way.

L2AUX is only writable in secure mode, which on GP devices implies
using a ROM call.  Nothing wrong with that.

-- 
Måns Rullgård
mans at mansr.com