In my current design, I use FM25 and AT25.
I have tied
WP to RESET common with ATMEGAs,
added 4053 mux on ISP lines, added pullup on CS,
pulldown on SCK, pullup on HOLD.
In fact I don't use HOLD nor WP actively.
As I remember, the absolute minimum to protect FM25 from losing the data when I program ATMEGA88 using SPI lines, was to use CS pullup, and that was enough.
Recently I wanted to clear up this madness. I have extremely dense PCB.
The plan is to ignore WP and HOLD (they have internal pullups as I understand since I have seen designd with thos pins unconnected, but I am unable to find in datasheet much more than vague recommendations to USE the pullups).
The best candidate for ellimination is RESET to WP connection.
I want to leave pullup on CS and pulldown on SCK (as recommended in one of ST micro appnotes).
The question is, how safe it is for autonomous robot to not use pullups on WP and HOLD. What am I risking? Can I tie them directly to Vcc or is this worse than leaving them floating? Brushed servomotors work nearby from the same battery, even if there are 2 firewalls from LDO and never had a problem with Vcc, I don't want to risk a single crash.