glad you got your problem sorted with a local patch to the kernel. That's the joy of open-source right there! :-)
Just a quick note: the driver in question is not specific to PostmarketOS. It's coming from mainline Linux:
So the "proper" way to suggest a change would be to subscribe to the relevant mailing lists, prepare a patch and send it to the list for review.
Looking at the file history, it seems like the buffer size was actually increased fairly recently:
And you could even reach out to the original author of the driver and ask why period_size is fixed. There might be a good reason after all: