NAPA, Calif. -- Antonio Brown left training camp again Sunday and while Mike Mayock said it was over the receiver's anger from being denied use of his helmet, the Oakland Raiders general manager also issued an ultimatum to Brown.

"You all know that AB is not here today, right?" Mayock told a group of beat reporters as practice began Sunday afternoon. "So, here's the bottom line -- he's upset about the helmet issue. We have supported that, we appreciate that. But at this point, we've pretty much exhausted all avenues of relief.

"So, from our perspective, it's time for him to be all-in, or all-out, OK? So, we're hoping he's back soon. We've got 89 guys busting their tails, we are really excited about where this franchise is going and we hope AB's going to be a big part of it, starting Week 1 against Denver. End of story. No questions, OK? Just wanted you guys to know where we were. Fair?"

"Here's the bottom line -- he's upset about the helmet issue. We have supported that, we appreciate that. But at this point, we've pretty much exhausted all avenues of relief. So, from our perspective, it's time for him to be all in, or all out, OK? So, we're hoping he's back soon."

Mike Mayock, on Antonio Brown

It has been an eventful and somewhat exhausting first Raiders camp for Brown, acquired in a March trade for a third- and a fifth-round draft pick. Because after being a mainstay during the team's offseason program, Brown began camp on the non-football injury list with frostbite on the soles of his feet thanks to a cryotherapy mishap in France in early July.

He left camp for two weeks seeking therapy for the feet, which included laser treatments.

Brown has also been upset with the league not allowing him to wear his Schutt Air Advantage helmet, the only helmet he's worn in his NFL career, because it is older than 10 years and, thus, no longer certified.

He returned to Napa on Tuesday and traveled with the team to Arizona for Thursday night's exhibition and ran routes and caught passes in pregame warm-ups. The Raiders were excited about Brown's return and after he was a full participant in Saturday morning's walk-through, the team anticipated him practicing fully as soon as Sunday.

"I'm not talking about it anymore," Raiders coach Jon Gruden said of Brown's helmet after the Arizona game. "It was a legal, certified helmet, you know? Somebody approved it, or he wouldn't have worn it."

Brown later responded critically to a Pro Football Talk report about his helmet issue with a tweet Saturday, calling out the NFL for "super prejudice."

In 24 days in Napa, Brown took a hot-air balloon ride at dawn on report day, participated in one pre-practice walk-through on July 28, was limited before leaving early on July 30, took part in pre-game warm-ups in Arizona on Thursday and was a full participant in Saturday's morning walk-through.

The Raiders were supposed to break camp Monday but ended a day early.

Asked earlier how much Brown changes the offense when he's on the field, Raiders offensive coordinator Greg Olson said:

"Significantly. He's one of the top players in the game. Any time you're able to have that kind of talent on the field, he's going to draw the attention of defensive coordinators and players. Just changes really dramatically when you have those type of players."