Make Macro That Loops Another Macro And Changes Value In A Cell?

I would like to make a macro that loops another macro and changes a value in a cell, like such:

Run macro
if cell A1 = cell A2
Stop
Else set value in cell A1 -0.1
Loop

How exactly would i do that?

I have a little bit:

Sub Macro2()
Call wantedmacro
With Range("A1")
If .Cells(1, 1).Value = "A2" Then Exit Sub
Else Range("A11").Value = (A1-0.1)
Call Macro2
End Sub