how do you find the subsystem of a file?

[daniel watson]

On Sat, Aug 21, 2021 at 12:30:27AM -0700, daniel watson wrote:
> i wrote a patch that got rejected because it did not apply cleanly to
> the tree of greg kh
> https://lkml.org/lkml/2021/8/18/304
> 
> the file i modified is
> drivers/staging/rtl8723bs/include/rtl8192c_recv.h
> 
> get_maintainer.pl gave me the list of emails to send the patch to,
> and i used it for that purpose.  the file
> Documentation/process/submitting-patches.rst says to see the T: entry
> for the subsystem in MAINTAINERS to find the right tree to base the
> patch on.  i tried searching through MAINTAINERS and found that there
> are a few subsystems that start with RTL8*.
> 
> greg kh is listed a few times in MAINTAINERS, so i'm not able to find
> the exact tree to start with by looking for the maintainer.
> 
> is there a systematic way of finding the subsystem, given a file?
> 
> in addition, how do i know what branch to use?  the T: entries have a
> repo, but not a branch name.
> 
> thanks!
> :wq, danny

answering my own question,

the output of

git log --oneline -1 <path>

should have the subsystem listed at the beginning.

thanks!

C-x C-c, danny