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List:       flashrom
Subject:    [flashrom] Re: flashrom failure report
From:       Nico Huber <nico.h () gmx ! de>
Date:       2022-08-01 19:57:34
Message-ID: e486448b-2dc8-02e1-11eb-1bb22169b840 () gmx ! de
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Hello Jen,

On 31.07.22 21:03, Jen Gilbert wrote:
> Hi, I'm trying to flash the rom of a bricked Chromebook. I've tried
> multiple times, removing and reattaching the ch341a. The rom chip is still
> attached to the motherboard (I've never soldered). Any help would be
> appreciated!

it looks like your connection to the SPI chip is just a little flaky.
Every time flashrom fails to read 0xff, only a single 1 bit is missing
(i.e. 0xfb: bit 2 is missing; 0xf7: bit 3 is missing etc.). Also, if
you look at the erased ranges, you'll see that some errors actually
vanished:

  > failed byte count from 0x00000000-0x00007fff: 0x3
  > failed byte count from 0x00000000-0x0000ffff: 0x2

So it seems reading is unreliable. But erasing works fine, writing
should too (but might also suffer from bit flips).

What you can do to enhance signal quality:

* Use shorter cables. < cm is recommended, sometimes <cm helps.
* Add series resistors to the data/control lines (MOSI, MISO, CS, CLK).

Hope that helps,
Nico
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