The easiest way to investigate this function is to graph it...hopefully on a graphing calculator which allows "sliders".
For P(x) > 0 m > 2; put another way for m>2, p(x) is strictly positive and has no real roots.
When m<2, p(x)<0 and again there are no real roots....that is
The graph suggests that there are no roots when m is other than 2 and when m=2, the graph is linear with root x=1
The question suggests that I may be missing something. If you find that I have misled you, I would appreciate some feedback to tell me what I missed. Thank you.