We report on our first set of results for charm physics, using a mixed-action setup with maximally twistedvalencefermionsonCLS𝑁𝑓 =2+1ensembles.Thissetupavoidstheneedofimprovement coefficients to subtract 𝑂(𝑎𝑚𝑐) effects. The charm quark mass, 𝐷 and 𝐷𝑠 decay constants are computed on a subset of CLS ensembles, which allows to take the continuum limit and extrapolate to the physical pion mass, and assess the scaling properties. Special attention is paid to the implementation of techniques to deal with systematic uncertainties. Our results show excellent prospects for high-precision computations on the full set of ensembles.