Re: RE: UART, pxa250

From: Chris McKillop (cdm@qnx.com)
Date: Thu Aug 01 2002 - 18:53:10 EDT


There is actually an errata on the PXA250 that states that on a resume the
first thing that must occur is a manual refresh of the DRAM. It seems they
are taking the DRAM out of self-refresh sooner then they are enabling the
DRAM control circuits, so if you don't do a manual refresh cycle the DRAM
could possibly errode.

    chris

--
Chris McKillop <cdm@qnx.com>     "The faster I go, the behinder I get."
Software Engineer, QSSL                   -- Lewis Carroll --
http://qnx.wox.org/
----- Original Message -----
From: "Jamey Hicks" <jamey.hicks@hp.com>
To: "vaibhav" <vaibhav@cse.ucsc.edu>; <cworth@east.isi.edu>
Cc: <bootldr@handhelds.org>
Sent: Thursday, August 01, 2002 10:02 AM
Subject: [Bootldr] RE: UART, pxa250
> Vaibhav, Carl,
>
> One thing that Brian noticed is that PocketPC on the h3900 is very
> sensitive to scribbling on dram -- or dram not being refreshed.  It will
> probably be helpful to disconnect the battery while doing bootldr work
> so that you can power it off for a couple of minutes to put dram into a
> zeroed state.
>
> Regarding your previous note about the sa1100.h vs pxa250.h: we think it
> would be best to use these files from the linux kernel.  They do not
> have the SA1100 prefix, so it is already one step towards something like
> you suggested.  The argument against using the corresponding files from
> Linux is that it would preclude a non-gpl bootldr.  Either way, the
> required files should be part of the bootldr source tree and should not
> have SA1100_ or PXA250_ prefixes on the defines.
>
> It would help if Vaibhav could go through and clean up the use of the
> SA1110 registers from sa1100.h.
>
> Finally, when Brian checks in his initial changes, we're going to put a
> #error directive in so that no casual users will try to compile and
> install the bootldr until we're sure it is stable.
>
> Jamey
>
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