  We revisit the constraints that Planck 2015 temperature, polarization and
lensing data impose on the parameters of warm inflation. To this end, we study
warm inflation driven by a single scalar field with a quartic self interaction
potential in the weak dissipative regime. We analyse the effect of the
parameters of warm inflation, namely, the inflaton self coupling $\lambda$ and
the inflaton dissipation parameter $Q_P$ on the CMB angular power spectrum. We
constrain $\lambda$ and $Q_P$ for 50 and 60 number of e-foldings with the full
Planck 2015 data (TT, TE, EE + lowP and lensing) by performing a Markov-Chain
Monte Carlo analysis using the publicly available code {\tt CosmoMC} and obtain
the joint as well as marginalized distributions of those parameters. We present
our results in the form of mean and 68 \% confidence limits on the parameters
and also highlight the degeneracy between $\lambda$ and $Q_P$ in our analysis.
From this analysis we show how warm inflation parameters can be well
constrained using the Planck 2015 data.
