[Bug 321] ftdi_eeprom often fails silently

bugzilla-daemon at bugzilla.openmoko.org bugzilla-daemon at bugzilla.openmoko.org
Thu Mar 29 06:49:32 CEST 2007


------- Additional Comments From werner at openmoko.org  2007-03-29 06:49 -------
More data: according to the data read back from the EEPROM, the board
where the IDs are okay and the board where they aren't, both a) have
indeed the EEPROM content ftdi_eeprom intended to write, and b) the
two EEPROM contents are identical.

A cursory check of the code in libftdi-0.9/src/ftdi.c:ftdi_eeprom_build
vs. the EEPROM content indicates that the EEPROM contains indeed what
was intended there. (E.g., that we don't have any integer size or byte
order issues.)

As a further verification step, I read back the EEPROM of my JTAGkey.
Now it gets spooky: that EEPROM contains only the IDs, but no strings.
However, usbview and lsusb happily print them. A quick search in
/usr/share/misc/usb.ids turned up neither the JTAGkey product ID, nor
any of the JTAGkey-specific strings. So it seems that this information
does indeed come from the USB device.

Also checked schematics and data sheets, for good measure. Everything
looks good there.

Closer inspection reveals that the string descriptors have quite
reasonable sizes, which indeed correspond to what lsusb et al. show.

Hmm. That looks interesting. If my suspicion is right, ftdi_eeprom
didn't get all too much testing with >64 words parts ...

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