Re: [PATCH AUTOSEL for 4.9 025/190] platform/x86: asus-nb-wmi: Add wapf4 quirk for the X302UA

[Sasha Levin]

On Thu, Mar 08, 2018 at 09:47:54AM -0800, Greg KH wrote:
>On Thu, Mar 08, 2018 at 09:39:14AM -0800, Darren Hart wrote:
>> On Thu, Mar 08, 2018 at 04:59:01AM +0000, Sasha Levin wrote:
>> > From: Santeri Toivonen <santeri.toivonen@xxxxxxxxxx>
>> >
>> > [ Upstream commit f35823619db8bbaa2afea8705f239c3cecb9d22f ]
>> >
>> > Asus laptop X302UA starts up with Wi-Fi disabled,
>> > without a way to enable it. Set wapf=4 to fix the problem.
>> >
>> > Signed-off-by: Santeri Toivonen <santeri.toivonen@xxxxxxxxxx>
>> > Signed-off-by: Darren Hart (VMware) <dvhart@xxxxxxxxxxxxx>
>> > Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
>>
>> Hi Sasha,
>>
>> I'm curious about this AUTOSEL tag, and what about this patch triggered
>> its selection?
>
>It's "magic"!  :)
>
>Seriously, it's close to magic, there's a tool that Sasha is using that
>takes "machine learning" to match patches that we have not applied in
>stable kernels to ones that we have, and try to catch those that we
>forgot to tag for the stable tree.  Not all subsystems mark stable
>patches, so this is an attempt to catch those fixes that should be
>getting backported but are not either because the developer/maintainer
>forgot to mark it as such, or because they just never mark those types
>of patches.
>
>Sasha has a better write up about how this all works somewhere, and
>given that this type of question keeps coming up every other week or so,
>I think I need to add it to a FAQ somewhere to point people at to make
>it more obvious what is happening.

It's pretty much a neural network that knows how to classify a "bug
fixing patch" based on things such as:

 - Code metrics
 - Words in the commit message (the NN knows about the 10,000 most used
   words, and their likehood to appear in a bug fixing patch).
 - Which files were modified.
 - Authors of the commit, and persons who got Cc'ed/Signed-off/etc.

So in this case, there are a few things that "helped" this patch get
selected:

 - The word "quirk" in the subject line.
 - "fix" + "problem" in the commit log.
 - Modifies drivers/platform/x86/asus-nb-wmi.c which contains mostly
   quirks.
 - The patch has minimal changes in code metrics. I don't have exact
   numbers for this, but it seems that in general patches that do very
little have more odds of fixing bugs.

And I also manually review all the stuff that get sent out, and to my
human brain it looks like something that should be in stable :)

-- 

Thanks,
Sasha