ac100 team mailing list archive

[Gordan Bobic <gordan@xxxxxxxxxx>]

On Wed, 17 Aug 2011 14:52:06 +0200, Gilles Grandou <gilles@xxxxxxxxxxx> 
wrote:
> Le 17/08/2011 14:35, Gordan Bobic a écrit :
> > On Wed, 17 Aug 2011 14:25:38 +0200, Marc Dietich <marvin24@xxxxxx> 
> > wrote:
> > > Hi Gordan,
> > >
> > > > Has anyone got the model/part numbers for the Micron chips used in 
> > > > the
> > > > AC100? Or the spec of the chips? I'm trying to find some larger 
> > > > capacity
> > > > chips that will be pin compatible.
> > >
> > > I forgot the extact number (must have been something like
> > > MT42L64M32D1KL-3 IT)
> > > but you will find out when you open it ;-)
> > >
> > > Note: there is a special code on the chips which you need to
> > > translate to the
> > > partnumber (http://www.micron.com/support/fbga.html).
> > >
> > > But I wonder how you will solder a bga...
> >
> > Thanks Marc. I was hoping it wasn't BGA, but these guys have 
> > re-chipped
> > non-DIY things for me before:
> > http://www.retronix.com/
> >
> > It'll probably cost a non-trivial fraction of a new AC100 (they are
> > cheap even by netbook standards nowdays), but it'll be worth it if 
> > it
> > leads to an ARM laptop with oodles of RAM. :)
> >
> > I just have to figure out what chips are going to be compatible 
> > (need to
> > find a Micron product list) and then find out what DIMMs have them 
> > on
> > (I'm crossing my fingers that crucial.com support guys may be able 
> > to
> > tell me that).
>
> My model is equiped with hynix chips, zoom on this picture:
>
> https://picasaweb.google.com/lh/photo/hQ22i6s8WS0NirVCix-qrw?feat=directlink

Not quite enough pixels in the image to see the numbers, but never 
mind, I'll be opening mine up soon to fit a 1280x720 screen (again) 
anyway.

> If you change chips you might have to upate register configurations
> in arch/arm/mach-tegra/board-paz00-memory.c

Correct me if I'm wrong, but wouldn't that only be required if the new 
chips have slower timings? The size and GPU allocations are given as 
kernel boot parameters (mem/nvmem) so the extra memory should be 
specifiable there. Or at least that's the theory I'm working on.

> However, I'm wondering how the bootstrap code would support new
> unknown RAM chips if they are not strictly compatible (I think RAM
> chips are described in the BCT partition, but its format is still
> unknown)

Well, that's just it - I'm hoping to find some RAM chips that are 
compatible (same width) and have timings that are at least as fast as 
what is currently fitted (this hopefully won't be an issue). Then the 
only thing to hope for is that the bootloader doesn't get confused by 
bigger RAM.

Gordan