If $f$ is a Maass form and $p$-Hecke eigenvalue (i.e. Hecke eigenvalue of usual Hecke operator $T_p$) of $f$ is $\lambda_f(p)$, do we know anything about lower bound of the sum$$S(x) = \sum_{x\le p\le 2x}|\lambda_f(p)|^2?$$

To avoid Confusion $$(T_pf)(z)=\frac{1}{\sqrt{p}}\left[\sum_{b=0}^{p-1}f\left(\frac{z+b}{p}\right)+f(pz)\right]$$ Any referecne would be highly helpful.