[Gta04-owner] Same GTA04 - now 33% faster :-)

[Dr. H. Nikolaus Schaller]

Am 25.07.2012 um 03:59 schrieb NeilBrown:

> 
> Sometimes bugs can be really useful.
> A patch that went into 3.5 causes the GTA04 to hang whenever the MPU clock
> speed is raised to 800MHz.  Apparently something to do with power routing -
> don't know the full story yet.
> 
> But while investigating this I discovered that my 3.x kernels were not
> pushing the GTA04 to 800MHz except for a moment or two at boot.  As soon
> as cpufreq is enabled, they drop back to 300MHz or 600MHz and never go back
> up again.
> 
> So I copied some code from board-omap3beagle.c and now get 800MHz on demand.
> The required patches have been published in my 3.5 branches.

Great.

> 
> So it isn't really that it is now 33% faster, but more that all this time it
> has been 25% slower than it should have been.
> 
> For further reading:
>  http://www.mail-archive.com/linux-omap@vger.kernel.org/msg72674.html

Regarding power routing: it is the same as the BeagleBoard XM and should
not have an influence.

The 800 / 1000 MHz variants of the DM3730 are not decoded by U-Boot,
although there is one bit in some system control register (in the same
128 bit block as the DIE_ID) which distinguishes between the 800 and
the 1 GHz specified chips. I think it is the "Speed Binned" register and/or the
"Control Device Status Register 15:0 (Address 0x4800 244C)" in
Table 1-6 of the TRM (SPRUGN4M).

I will take a look into the U-Boot/X-Loader code to fix that it is reported
correctly.

BTW: all of them can be overclocked as the OpenPandora guys have done.
If I remember correctly they could go to 1.2 GHz for the 600 MHz OMAP3530,
i.e. factor 2.

> 
> NeilBrown
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