There is not, but maybe there is.
If your code stops somewhere where the debugger can not show you a source line (for whatever reason, even if there it is a bug) then it will open the asm. The debugger insists on showing you where you stopped.
In some case, like exception, it will show you the source of calling code (lower down the stack frame), but that is limited to exceptions.
If you (as you said) "stepped" F7fF8, then the debugger wants you to show the real pos where you are at.
F7/F8 should have stepped to the next source line. So it should not stop in asm code (and if it didn't there wouldn't be an asm window). Unfortunately either GDB or FPC (or the combination of both) have a bug => and F7/F8 stops incorrectly.
For this specific case there is a setting.
Tools > Options > Debugger: There is a property grid. Find the option "FixIncorrectStepOver". The IDE will try its best to correct the wrong step. Usually that works well. No known side effects yet, almost. Occasionally (rarely) you need to do F8 twice, because the first F8 only step half a line (and appears not to have moved at all).
There also is "automatically close asm window, after source not found". This will close the asm window, when you press F7/F8 again. (assuming that returns you to a pos with source).
And there is fpdebug. It does not have the above bug. It will open the asm, if you do asm-stepping. But that is kind of desired / by design.