When you press /, it says
Enter CONFIG_ (sub)string to search for (with or without "CONFIG_")
which means it's looking for the names of the options, not the labels of the options.
With Linux 3.3, I found your option using grep...
$ find . -name Kconfig -exec grep 'config.*PCI' {} + | grep DMA
./drivers/ide/Kconfig:config BLK_DEV_IDEDMA_PCI
And then opened the file ./drivers/ide/Kconfig to see more information
config BLK_DEV_IDEDMA_PCI
bool
select BLK_DEV_IDEPCI
select BLK_DEV_IDEDMA_SFF
Since it doesn't have a tristate or bool line like the others, that suggests it doesn't appear in the menu.
Searching in the same file for BLK_DEV_IDEDMA_PCI, you can see lots of entries that refer to it, e.g.
config BLK_DEV_AMD74XX
tristate "AMD and nVidia IDE support"
depends on !ARM
select IDE_TIMINGS
select BLK_DEV_IDEDMA_PCI
So it looks like you're not supposed to enable DMA explicitly: the drivers that need DMA will enable it automatically.
It could be interesting to clone the git repository of linux and query it immediately.
Cloning the repo
Beware it's a large file! (~1.5G)
Install git and run the following (in a new directory):
git clone http://github.com/torvalds/linux.git
Querying the repo
Once you've cloned it, you can analyze the log of commits with git log.
Since the log is so long, you may want to limit your research to a smaller period of time:
git log <since>..<to>
for instance
git log v3.4..v3.5
This has theoretically a lot of info you could use. For example, that command prints the 20 most prolific committers along with their number of commits and their email address.
$ git log v3.4..v3.5 | grep Author | cut -d ":" -f 2 | sort | uniq -c | sort -nr | head -n 20
417 Linus Torvalds <torvalds@linux-foundation.org>
257 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
196 Mark Brown <broonie@opensource.wolfsonmicro.com>
191 Axel Lin <axel.lin@gmail.com>
172 David S. Miller <davem@davemloft.net>
138 Daniel Vetter <daniel.vetter@ffwll.ch>
132 H Hartley Sweeten <hartleys@visionengravers.com>
128 Al Viro <viro@zeniv.linux.org.uk>
117 Stephen Warren <swarren@nvidia.com>
113 Tejun Heo <tj@kernel.org>
111 Paul Mundt <lethal@linux-sh.org>
104 Johannes Berg <johannes.berg@intel.com>
103 Shawn Guo <shawn.guo@linaro.org>
101 Arnd Bergmann <arnd@arndb.de>
100 Thomas Gleixner <tglx@linutronix.de>
96 Eric Dumazet <edumazet@google.com>
94 Hans Verkuil <hans.verkuil@cisco.com>
86 Chris Wilson <chris@chris-wilson.co.uk>
85 Sam Ravnborg <sam@ravnborg.org>
85 Dan Carpenter <dan.carpenter@oracle.com>
The email address can give you an idea about the employers of the developers (google.com, cisco.com, oracle.com).
Best Answer
You can use lkml.org to search through the archive. It's unofficial!
excerpt
There are others as well:
Tips for searching
If you drill in enough to the lkml.org site you'll find a search box, like here for example:
Additionally I would suggest leveraging the power of Google to help with this. Most of these types of sites suck in comparison as to what you can search with using Google.
For example:
Put this in your search bar if you want to find everything on lkml.org related to NFS!