What is the test for damages under the Eighth Amendment for injuries sustained in prison brutality?

In a Bivens action, "damages may be obtained for injuries consequent upon a violation of [the Constitution] by federal officials." 403 U.S. at 395, 91 S.Ct. at 2004. Alleged prison brutality is "part of the total punishment to which the individual is being subjected for his crime and, as such, is a proper subject for Eighth Amendment scrutiny." Ingraham v. Wright, 430 U.S. 651, 669, 97 S.Ct. 1401, 1411, 51 L.Ed.2d 711 (1977). However, "[a]fter incarceration, only the unnecessary and wanton infliction of pain ... constitutes cruel and unusual punishment forbidden by the Eighth Amendment." Id. at 670, 97 S.Ct. at 1412. Further,