[flashrom] Trouble disabling write-protection on Chromebook

[David Hendricks]

On Mon, Dec 16, 2013 at 9:14 AM, <
BM-2cWKH3wgq8zXX9eHfba16oTc8b61ead4Yq at bitmessage.ch> wrote:

> Hello flashrom developers,
>
> I'm having trouble disabling write-protection on my Samsung Arm
> Chromebook. So far I've removed the metallic sticker covering the
> "write-protect screw hole" according to the pictures on the Chromium wiki
> <
> http://www.chromium.org/chromium-os/developer-information-for-chrome-os-devices/samsung-arm-chromebook
> >.
> On the Snow board, this hole ships with no screw in it.


Are you sure about that? There should be a screw there...


> As root in
> developer mode, the output of flashrom -v is "flashrom v0.9.4  : 4169bc8
> ...". The first time I ran flashrom --wp-disable, I got a message saying
> the operation FAILED with error=1. At that point I took the board apart
> again and cleaned the write-protect screw hole with q-tips dipped in
> rubbing alcohol. When I reassembled the Chromebook and tried again with
> flashrom -V --wp-disable, the last few lines I receive are:
>
> w25_set_srp0: old status: 0xb8
> w25_set_srp0: new status: 0xb8
> w25q_disable_writeprotect(): error=1.
> No -i argument is specified, set ignore_fmap.
> FAILED
> restore_power_management(): Power management enabled
>
> As you can see, I can't seem to disable write protection on this chip. I'm
> running stock ChromeOS. Any idea what I might be doing wrong? Thanks in
> advance.


That's weird... Since you have the system taken apart already, can you try
disconnecting the battery while the machine is unplugged? I'd recommend
leaving it disconnected for a minute or so, the idea being to give the SPI
ROM enough time to fully discharge and reset.

If you have a voltmeter handy, you can also try measuring the voltage on
the /WP pin (pin 3). More details on pin configuration can be found in the
datasheet:
http://www.winbond-usa.com/hq/enu/ProductAndSales/ProductLines/FlashMemory/SerialFlash/W25Q32DW.htm

-- 
David Hendricks (dhendrix)
Systems Software Engineer, Google Inc.
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