The (pre-merger) requirement for breakfast is that they offer a continental breakfast, for 2 people.
Some go beyond this, by offering a buffet breakfast, or a buy-up to a buffet breakfast, or $X off the menu when ordering a la carte. and some offer just the required level of a continental breakfast.

There is a thread with a wiki listing the breakfast options at many but not all SPG properties; the 4P you stay at isn't listed.

Post How Properties handle the SPG Platinum Breakfast Benefit introduced in 2012