MTK based phones

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Harald Welte laforge at
Sun Nov 27 07:13:56 UTC 2011

Hi Marcin and Martin,

On Sun, Nov 27, 2011 at 01:17:37AM +0100, Marcin Mielczarczyk wrote:
> > On the other hand, I have access to very cheap phones using Infineon
> > PMB7880 (C166 + DSP) or MTK (ARM9) chipsets.
> Note, that on the market there is much more Mediatek phones based on ARM7
> (MT622x) than on ARM9 (MT623x).


> My Linux port for this architecture didn't touch L1 at all. I focused first
> on getting "application" cpu up and running.
> I managed to configure TX path to transfer data on given frequency and
> after that I had to have DSP running to send "proper" data.

All of this, once again, quite amazing work you've been pulling off.  I
really regret that nobody (including myself) has ever since picked up on
it :(

> I got stack on DSP part, because I tried first to download firmware from
> DSP ROM. This didn't work out so far.
> Better approach would be to disassemble and understand DSP-ARM API and use
> it as it is, without firmware changing for now.

Indeed, I agree, the best approach (like we took on Calypso) is to try
to use the DSP ROM code as-is.  This reduces the required work to:

1) understand how to bring up (boot/start) the DSP from the ARM
2) understand how to drive the API from the ARM and feed instructions
   into the DSP as well as read results
3) writing the required scheduler around those instruction/result
   primitives, possibly porting/re-using some of the calypso L1 scheduler

> Unfortunately I couldn't find time to work on that due to my professional
> work.

We can all understand that, but it's a real pity...

- Harald Welte <laforge at> 
"Privacy in residential applications is a desirable marketing option."
                                                  (ETSI EN 300 175-7 Ch. A6)

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