[flashrom] Can't probe AT26DF321 on OptiPlex 755

Ondrej Zary linux at rainbow-software.org
Wed Aug 12 08:26:09 CEST 2015


On Wednesday 12 August 2015, Patrick 'P. J.' McDermott wrote:
> Hi,
>
> I have a Dell OptiPlex 755 USFF which has an Atmel AT26DF321 SPI flash
> chip (which is like an AT25DF321 and has the same device ID except it
> doesn't have a HOLD# pin).  I've used flashrom to read and write the
> same chip on another board by ISP using a BeagleBone Black, 10-cm jumper
> cables, a SOIC clip, and an ATX PSU.
>
> However, flashrom with the same ISP setup fails to probe the chip on the
> OptiPlex.  I've tried two different known-working BBBs, different
> cables, two different Pomona SOIC clips, connecting WP# to 3.3 V,
> connecting what would be HOLD# on the AT25 to 3.3 V, and different
> spispeed clock frequencies from 1 kHz to 10 MHz.
>
> I've tried powering the chip (and the rest of the board's 3.3-V rail)
> with a 3.3-V line of the ATX PSU, and I've tried instead powering the
> whole board with the computer's 12-V PSU.  I've also tried running
> flashrom while holding down the power button to keep the system in
> reset.  Following some advice on <http://flashrom.org/ISP> I even tried
> removing the DIMMs and CPU.
>
> Every time I get only bytes of 0xff from the chip, as in the attached
> log.  In my experience that usually means either the programmer isn't
> properly connected to the chip or the programmer uses a different data
> voltage than the chip does.  But I've checked and rechecked all of the
> connections, and I know both the BBB and the AT26DF321 use 3.3-V data
> signals.
>
> Unfortunately there don't seem to be any schematics available for this
> board (Dell model number 0HX555, ODM model number HX533 A00, ODM might
> be Asustek or MiTAC).  This system does have an Intel Management Engine
> in the northbridge, but even if that was running I should at least be
> able to probe the chip and read its contents.
>
> Does anyone have any ideas of anything else I could try (short of
> desoldering the chip from the board) or about what the problem may be?
>
> Thanks,

Try installing the SERVICE_MODE jumper - it should disable the management 
engine.

-- 
Ondrej Zary




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