Mediatek MT6235 status (Sciphone G2)

Marius Cirsta mforce2 at gmail.com
Fri Feb 18 18:54:46 UTC 2011


On Fri, Feb 18, 2011 at 7:55 PM, Harald Welte <laforge at gnumonks.org> wrote:
> On Fri, Feb 18, 2011 at 07:27:59AM -0700, Marius Cirsta wrote:
>>  From what I understand MT6235 has just one ARM926EJS processor and a
>> DSP.  This probably means that the it runs both the application and
>> the GSM stack on a single CPU , right ?
>
> It's actually 2 DSP cores.  But yes, your last statement is correct.
>

Didn't read the datasheet that well it seems.

>>  I read in an article about Symbian that it's able to do this because
>> it's a realtime OS but to my knowledge Linux is not ( hence the GSM
>> stack runs on a second processor in Android phones ). Now I also know
>> there's a realtime Linux kernel but the question is would it be
>> possible to run both the application and GSM stack together on the
>> MT6235 under Linux.
>
> Don't believe marketing crap by any company (or the Symbian foundation) ;)
>

I usually don't but since I have only basic knowledge in telecom I
thought what they said was true and it did acutally make sense.

> Layer 2 and Layer 3 of GSM have no realtime requirements, it's only the L1
> that has.  Running L1 inside the kernel in IRQ priority should solve all those
> problems.  If not, we can still use the FIQ to pre-empt all the other IRQs
> in the kernel.
>
> Layer2 + Layer3 then run as regular userspace programs on top of the kernel.
>
> The entire' "realtime vs. non-realtime" debate often seems nothing but
> a religious and/or marketing war.
>

Thanks for these clarifications , it answers my question. I do have
another one though , out of curiosity. Why do most if not all Android
phone have a separate core for running the GSM stack ? Even MT6516 has
a dedicated ARM 7 core. I cand think of the advantages being isolation
of the GSM stack and keeping it hidden and proprietary but until now I
thought it was a must.

> Regards,
>        Harald
> --
> - Harald Welte <laforge at gnumonks.org>           http://laforge.gnumonks.org/
> ============================================================================
> "Privacy in residential applications is a desirable marketing option."
>                                                  (ETSI EN 300 175-7 Ch. A6)
>




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