Newest kernel appears to break tap feature - good starting point for kernel development?

Newest kernel appears to break tap feature - good starting point for kernel development?

[Reza]

Hi all,

I'm interested in getting involved in kernel development. I compiled the 
latest kernel and found that it broke the tap feature on my asus x54h 
k54l. I had a look at the way the devices were interpreted and 
/proc/bus/input/devices gave different results. This seems like it may 
be a good starting point but I'm not sure where to go from here or 
whether it's an issue with the kernel. I presume it is as switching back 
to the older kernel fixes the tapping for left click. Any advice on 
where to go from here would be greatly appreciated. Thanks.

Reza


-works fine-

Linux laptop 3.1.0-1-amd64 #1 SMP Tue Jan 10 05:01:58 UTC 2012 x86_64 
GNU/Linux

I: Bus=0011 Vendor=0002 Product=0001 Version=0063
N: Name="PS/2 Logitech Wheel Mouse"
P: Phys=isa0060/serio4/input0
S: Sysfs=/devices/platform/i8042/serio4/input/input6
U: Uniq=
H: Handlers=mouse0 event6
B: PROP=0
B: EV=7
B: KEY=70000 0 0 0 0
B: REL=103


-latest kernel where the tap feature breaks-

Linux laptop 3.3.0-rc2+ #5 SMP Fri Feb 3 21:05:27 GMT 2012 x86_64 GNU/Linux

I: Bus=0011 Vendor=0002 Product=000e Version=0000
N: Name="ETPS/2 Elantech Touchpad"
P: Phys=isa0060/serio4/input0
S: Sysfs=/devices/platform/i8042/serio4/input/input6
U: Uniq=
H: Handlers=mouse0 event6
B: PROP=0
B: EV=b
B: KEY=6420 30000 0 0 0 0
B: ABS=260800011000003

Newest kernel appears to break tap feature - good starting point for kernel development?

[Mulyadi Santosa]

Hi Reza....

On Sat, Feb 4, 2012 at 05:11, Reza <vivi@mage.me.uk> wrote:
> Hi all,
>
> I'm interested in getting involved in kernel development. I compiled the
> latest kernel and found that it broke the tap feature on my asus x54h
> k54l. I had a look at the way the devices were interpreted and
> /proc/bus/input/devices gave different results. This seems like it may
> be a good starting point but I'm not sure where to go from here or
> whether it's an issue with the kernel. I presume it is as switching back
> to the older kernel fixes the tapping for left click.

Likely you found regression here.

I think the key here is by using git feature called "bisect" to find
out the culprit. This might require repetitive kernel build and re
test. It's kinda trial work, only here you got help from git as the
revision control.

Once you found the commit that introduce the bug, you can either
remove that (of course, without introducing instability) or improve
it.

It all might sound easy, but require patience and time.

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com