RE: [ECOS] J3 flash lockbits across reset

["Stephen Goadhouse" <stephen dot goadhouse at adiengineering dot com>]

> -----Original Message-----
> From: ecos-discuss-owner@ecos.sourceware.org 
> [mailto:ecos-discuss-owner@ecos.sourceware.org] On Behalf Of 
> Gary Thomas
> Sent: Thursday, January 12, 2006 8:22 AM
> To: Andrew Lunn
> Cc: alfred hitch; eCos Discussion
> Subject: Re: [ECOS] J3 flash lockbits across reset
> 
> On Thu, 2006-01-12 at 09:44 +0100, Andrew Lunn wrote:
> > On Thu, Jan 12, 2006 at 03:33:03AM -0500, alfred hitch wrote:
> > > Hi,
> > > 
> > > I am confused on what is the correct behavior across power resets 
> > > (of hardware) for J3 flash'es.
> > > 
> > > 1) Will all sectors which were locked before power reset, 
> remain so ?
> > > 
> > > I am confused by some posts on net, saying they get 
> locked (all) by 
> > > default across resets (irr. of before power reset status)
> > > 
> > > Some say, it is unlocked (all blocks )by default  across resets.
> > > 
> > > I dont think flash should change status across resets. It should 
> > > preserve whatever I locked before reboot and vice versa.
> > 
> > The data sheet for the chip is the best source of answer for this 
> > question.
> > 
> 
> The J3 devices are different from most other FLASH devices - 
> all sectors are *always* locked after a device reset.  This 
> is just how the hardware works.
> 
> --
> ------------------------------------------------------------
> Gary Thomas                 |  Consulting for the
> MLB Associates              |    Embedded world
> ------------------------------------------------------------

This is incorrect.  You must be thinking of the new Intel P30 Flash.  For
the old reliable J3 Flash, the lock bits are stored in non-volatile Flash
cells and survive a reset/power cycle.  If you lock a sector in J3 Flash,
it stays locked, through resets and power cycles, until the "unlock all
sectors" command is given.

The new Intel P30 Flash is like you describe.  The lock bits are stored
in volatile memory. All sectors are in the lock state whenever you reset
the chip or power cycle. Any sectors that you unlocked will not be
remembered through resets/power cycles.  You have to always unlock
sectors before writing to them.  It's a super pain!  Apparently some
older Intel Flash series also did this and for some reason they brought
back this stupid feature.  It totally goes against what RedBoot expects
from Flash.


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_/  Stephen Goadhouse                 Work: (434) 978-2888 x254 _/
_/  Senior Staff Engineer  stephen.goadhouse@adiengineering.com _/
_/  ADI Engineering               http://www.adiengineering.com _/
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