Is DR/magic weak to all spells, or does it resist spells that cause physical damage?

Ok, so one of the characters in our game is getting DR and is arguing that any damage caused by any spell bypasses the DR.

A creature with this special quality ignores damage from most weapons and natural attacks. Wounds heal immediately, or the weapon bounces off harmlessly (in either case, the opponent knows the attack was ineffective). The creature takes normal damage from energy attacks (even nonmagical ones), spells, spell-like abilities, and supernatural abilities.

The rest of the group is in agreement though that if a spell causes physical damage as opposed to energy or straight magic (like magic missile), then DR should apply. He gave the example of bombardment, saying that because the rocks are created by magic that it counts as a magical damage. The spell doesn’t specifically say a damage type, but obviously the damage is caused by the rocks falling, and not any sort of magic (since it references a non-magical avalanche in the spell). But if you conjure a non-magical animal, that animal’s attacks don’t automatically become magical because it was summoned magically. So, should DR reduce the physical types of damage from spells, or would throwing a rock with a spell count as magic damage as well? *note, the DM already ruled in favor of DR reducing bludgeoning, slashing, etc from spells, so it doesn’t actually effect the rest of us and if he gets his own character killed then so be it. I would actually just like clarification on it because I can’t find anything about it.