The team officially designated Ingram to return to practice from the physically unable to perform list Tuesday, the day the team had to decide whether to place the 2012 first-round draft choice on season-ending injured reserve or begin his 21-day practice period.
Ingram is less than six months removed from reconstructive knee surgery, which he had May 21. He tore the anterior cruciate ligament in his left knee May 14 in an offseason workout at the team facility.
The latest the Chargers will be able to activate him is for the game against the Denver Broncos on Dec. 12, nearly seven months after his surgery.
"We'll look at obviously the best interest of Melvin and the health of his knee," coach Mike McCoy said Monday, when asked what will go into the organization making that decision. "And understand what we want to do moving forward with him. And we have a plan in place. We'll let you know that as soon as we want to let everybody know."
ESPN.com Chargers reporter Eric Williams contributed to this report.