[flashrom] M25P16, erase (ok) and write (not ok)

[Stefan Tauner]

On Thu, 17 Oct 2013 10:20:47 +0200
Raven <originalraven at hotmail.com> wrote:

> Hello,
> here are the test results for "Found Micron/Numonyx/ST flash chip 
> "M25P16" (2048 kB, SPI)".
> Erase seems to work, but write fails.
> I tried it with an Arduino Uno 
> (http://www.flashrom.org/Serprog/Arduino_flasher).

Hi and thanks for your report!

I think the most probable causes are 1) a flaky chip, 2) flaky
connections, but I am not sure.

To test for flaky connections please re-read the chip a few times
and compare the results. One way to do that is using the verify
command multiple times:
./flashrom -p serprog:dev=/dev/ttyACM0:2000000 -Vv test.rom 

If it always fails like it did for writing (first byte/failure being
Expected=0x55, Found=0x4b, and a total of 0x8399d unexpected bytes),
then at least the clock, MISO and MOSI connections should be ok.

What happens if you write the same image again? The number of
unexpected bytes seems rather huge to me (more than half a MB) to be
just a flaky chip, but erasing apparently works, so it cant be a simple
write protection. What does the following command print out?
hexdump  -e '/1 "%02X\n"' test.rom | grep -v FF -c
(it should show the number of bytes in test.rom that are not all ones,
i.e. 0xFF).

> Output is attached.

Please do not compress log files in mails here.
-- 
Kind regards/Mit freundlichen Grüßen, Stefan Tauner