  We propose a new method to compute nonlinear transport coefficients in
holography, such as nonlinear DC conductivity and nonlinear friction
coefficient. The conventional method can be applied only to the models whose
action in the gravity dual has the ``square-root structure,'' i.e., the
Dirac-Born-Infeld action of the probe D-branes or the Nambu-Goto action of the
probe strings. Our method is applicable to a wider range of holographic models
whose action does not have such a square-root structure. Our method is based on
the requirement of regularity, and we propose a condition for regularity in the
form of two simultaneous equations, which we call the patchwork condition. Our
method also enables us to estimate the effective temperature of the
nonequilibrium steady states in a wider range of holographic models. We show
that a general model exhibits different effective temperatures for different
fluctuation modes.
