Hello Adam,
Of course the info is helpful, thank you for sending a message.
I checked very quickly the datasheet for GD25LB128DSIG, and it has the same Device ID as that group of chips which is already added, 'GD25LQ128C/GD25LQ128D/GD25LQ128E', that is why it was recognised like this. Since you said it not only recognised, but also worked, potentially the chip name can be just added to the group. But to decide on that, all the fields in the existing chip definition for 'GD25LQ128C/GD25LQ128D/GD25LQ128E' need to be checked against the datasheet for GD25LB128DSIG. If there is a difference, then GD25LB128DSIG will need to have its own definition (with the same id).
If you have time/interest, you are very welcome to check the datasheet and either update the existing definition or add a new one. We have some docs on how to do it: https://www.flashrom.org/dev_guide/development_guide.html https://wiki.flashrom.org/Development_Guidelines#Adding/reviewing_a_new_flas...
The second doc is an old one and has room for improvement. I am planning to update it later this year, but for now that's what we have. If you will be trying to send a patch to add support for a chip, you are welcome to complain if the docs are incomplete or unclear.