[flashrom] SOIC8 test clip - cant write to BIOS SPI flash chip

[Nico Huber]

On 22.10.2015 00:24, Denis 'GNUtoo' Carikli wrote:
> On Sat, 17 Oct 2015 12:57:54 +0200
> Nico Huber <nico.h at gmx.de> wrote:
>> I'd try with the AC adapter. In that case Vcc must _not_ be connected
>> to your programmer. GND, OTOH, has to stay connected.
> If that happens, could the EC be destroyed? or the laptop power system?
> I've a laptop that doesn't lit its leds once a power supply is
> connected to it. I broke it while messing with reflashing after trying
> to test ME related stuff on it.
It's more likely to break a power supply. If you connect different Vcc
sources you might get a current flowing in the wrong direction at the
weaker source.

> On Sat, 17 Oct 2015 12:57:54 +0200
> Nico Huber <nico.h at gmx.de> wrote:
>>> so that this Vcc pin would be powered by them, or it is forbidden
>>> to do it while using SPI programmer in the same time?  
>> Not forbidden. It's sometimes even encouraged because there are boards
>> where the Vcc pin of the flash chip is directly connected to other
>> chips, which would draw down the power from the programmer.
> Robert, I think it can be detected by measuring the voltage at the pins
> of the SPI programmer before and after plugging the clip.
> Nico, Are there other common issues of the same kind with laptops?
Doing ISP on a board that's not designed for ISP gives issues all over
the place. Most can be worked around with very low clocks and a good
power supply. But if you get reliable reads, writing usually works too
(if there's no write protection).

Nico