cannot read/write thinkpad R500 chip AT25DF321

[Spenser Truex]

I'm trying to libreboot my r500 thinkpad but can't do a consistent read.
I've librebooted many T500s without issue.

bug at libreboot

https://notabug.org/libreboot/lbmk/issues/30

Issue is with flashrom though. Perhaps something about this chip in
particular? Any ideas moving forward?

Best regards,

[Alexander 'lynxis' Couzens]

Hi Spenser,
> Issue is with flashrom though. Perhaps something about this chip in
> particular? Any ideas moving forward?

you should check the power supply and try to improve the signals of your
SPI bus.

power supply => either your power supply at all isn't sufficient or the
spi chip draws too quick power that an additional capacitor (of
the correct size) closer to the chip is required.

signal => improve your cables, shielding, reduce EMI or
desolder the chip and put it on a seperate board, etc.. Or reduce the
spi speed, what you already did. Maybe use a different spi clip or
solder cables on top of your spi chip instead of using a clip.

in-system flashs are always special and depend on the PCB of your
target board. Some boards aren't possible to flash at all. But you
should be ok (there is a low chance of bricking).

For sure there are bugs in flashrom. But usually it's power or signal
integrity. If it's an bug within flashrom, I would also desolder the
chip and solder it to a small debug board. So you could reduce other
failures soures and test flashrom in a "known" environment.

Best,
lynxis

[Spenser Truex]

On 21/08/16 07:58PM, Alexander 'lynxis' Couzens wrote:
> Hi Spenser,
> > Issue is with flashrom though. Perhaps something about this chip in
> > particular? Any ideas moving forward?
>
> you should check the power supply and try to improve the signals of your
> SPI bus.
>
> power supply => either your power supply at all isn't sufficient or the
> spi chip draws too quick power that an additional capacitor (of
> the correct size) closer to the chip is required.
>
> signal => improve your cables, shielding, reduce EMI or
> desolder the chip and put it on a seperate board, etc.. Or reduce the
> spi speed, what you already did. Maybe use a different spi clip or
> solder cables on top of your spi chip instead of using a clip.
>
> in-system flashs are always special and depend on the PCB of your
> target board. Some boards aren't possible to flash at all. But you
> should be ok (there is a low chance of bricking).
>
> For sure there are bugs in flashrom. But usually it's power or signal
> integrity. If it's an bug within flashrom, I would also desolder the
> chip and solder it to a small debug board. So you could reduce other
> failures soures and test flashrom in a "known" environment.

Thanks for this, I got another SOIC clip since mine had degraded and
bent leads.

I am going to put in a T500 board in the R500 to make a frankenpad
solution, since T500 boards have always worked fine for me and only cost
$25.

I've made a couple dozen of these laptops and am very happy with the
process and demand.
> Best,
> lynxis
> --
> Alexander Couzens
>
> mail: [e-mail]
> jabber: [e-mail]
> gpg: 390D CF78 8BF9 AA50 4F8F  F1E2 C29E 9DA6 A0DF 8604

[Spenser Truex]

On 21/08/16 07:58PM, Alexander 'lynxis' Couzens wrote:
> Hi Spenser,
> > Issue is with flashrom though. Perhaps something about this chip in
> > particular? Any ideas moving forward?
>
> you should check the power supply and try to improve the signals of your
> SPI bus.
>
> power supply => either your power supply at all isn't sufficient or the
> spi chip draws too quick power that an additional capacitor (of
> the correct size) closer to the chip is required.
>
> signal => improve your cables, shielding, reduce EMI or
> desolder the chip and put it on a seperate board, etc.. Or reduce the
> spi speed, what you already did. Maybe use a different spi clip or
> solder cables on top of your spi chip instead of using a clip.
>
> in-system flashs are always special and depend on the PCB of your
> target board. Some boards aren't possible to flash at all. But you
> should be ok (there is a low chance of bricking).
>
> For sure there are bugs in flashrom. But usually it's power or signal
> integrity. If it's an bug within flashrom, I would also desolder the
> chip and solder it to a small debug board. So you could reduce other
> failures soures and test flashrom in a "known" environment.

Hello again,

I ordered a new R500, it happens to have the AT26DF321 chip also.
Flashrom -L says it doesn't support it. So I'm inclined to think support
for this chip doesn't exist, unless one of the other labels is actually
secretly the same chip.

So, how can I determine which solution out of those given above is needed
for this chip?

Thanks!
> Best,
> lynxis
> --
> Alexander Couzens
>
> mail: [e-mail]
> jabber: [e-mail]
> gpg: 390D CF78 8BF9 AA50 4F8F  F1E2 C29E 9DA6 A0DF 8604

#2, this chip

[Spenser Truex]

If this chip is in fact not supported, I'd be happy to donate this board
to someone who wants to add support for it. It must be common if I've
gotten two in a row.

I already tried replacing the SOIC clip and buying shorter jumper
cables.
> mail: [e-mail]
> jabber: [e-mail]
> gpg: 390D CF78 8BF9 AA50 4F8F  F1E2 C29E 9DA6 A0DF 8604

#2, this chip

[Nico Huber]

Hi Spenser,

On 19.08.21 21:44, Spenser Truex wrote:
> If this chip is in fact not supported, I'd be happy to donate this board
> to someone who wants to add support for it. It must be common if I've
> gotten two in a row.

the chip is indirectly supported. It uses the same identification as the
AT25DF321, so flashrom should detect it as that. It's also the only chip
model to be expected on a R500 mainboard, as far as I have seen in the
schematics.
> I already tried replacing the SOIC clip and buying shorter jumper
> cables.

Still, the problem you are facing is most likely a hardware issue. You
are not looking for something specific to the flash chip (these SPI
chips are all very similar); but something that is specific to the main-
board design or your flash programmer or the connection. AFAICT, you
haven't mentioned yet what programmer you are using, so it's hard to
guess anything.

Also, how do you power the flash chip? Do you use the laptop's AC
adapter? or do you try to power it with your flash programmer? In
the latter case, you'll also have to expect to power half of the
mainboard as the power rail is directly connected to flash chip,
AFAICS (this is not recommended btw.).

Keep in mind that every mainboard (that is not designed to be flashed
like this) is different. When powering the flash chip via a clip, most
people just succeed by luck with the right amount of power (too little
and the flash chip won't work, too much and more parts of the mainboard
wake up).

Nico