RE: [ECOS] J3 flash lockbits across reset

[Gary Thomas <gary at mlbassoc dot com>]

On Thu, 2006-01-12 at 08:40 -0500, Stephen Goadhouse wrote:
> > -----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.

> 
> 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.

Sorry, you are correct (I recently did some work with the P30 FLASH
devices and they were fresh in my mind, just not the moniker)

-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
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