[itex]\frac{\partial}{\partial y}\left(m\frac{dy}{dx}\right)=0[/itex]

where [itex]y[/itex] is a function of [itex]x[/itex] and [itex]m[/itex] is a function of [itex]y[/itex]. If I integrate this equation first with respect to [itex]y[/itex] should I get a function of [itex]x[/itex] as the constant of integration (say [itex]C\left(x\right)[/itex]) or it is just a constant? If it is a function, how can I then find its form (e.g. polynomial, etc.)? Should I use boundary conditions or I can decide about the form from inspecting the type of the equation.