Re: Regression since commit 92bac83

From: Larry Finger
Date: Mon Oct 19 2015 - 11:55:26 EST


On 10/19/2015 03:08 AM, Hans de Goede wrote:
Hi,

On 19-10-15 01:59, Larry Finger wrote:
Hi,

I recently upgraded the kernel in a Dell Latitude D600 and found that the
touchpad clicks failed. The problem was bisected to commit
92bac83dd79e60e65c475222e41a992a70434beb ("Input: alps - non interleaved V2
dualpoint has separate stick button bits"). The laptop has a combination
touchpad and control stick. For this device, the following values are found:

priv->protoversion is 0x200 (ALPS_PROTO_V2)
priv->flags is 0x6 (ALPS_DUALPOINT | ALPS_PASS)

As a result, the new code added in this patch is executed, and left, right,
and middle are updated. Once this code is introduced, a left click causes some
event as it will wake a sleeping screen, but not select any windows or do
anything useful.

Please advise on what information would be needed to help debug this problem.

Can you build a recent upstream kernel from source, and when building it
comment out these lines in drivers/input/mouse/alps.c, around lines 2555 - 2556

if (dmi_name_in_vendors("Dell"))
priv->flags |= ALPS_DELL;

That should fix things, if that fixes things we need to rename the flag
and move to a list of dmi-matched models (rather then vendor) where the new
behavior
introduced by the patch causing you problems is actually necessary.

Step 1 is confirming that not setting the flag fixes things for you,
if you can get back to us confirming that, then I'll whip up a patch
to switch to model matching (which is not ideal, but seems to be
necessary).

Thanks for the quick response. Removing the two lines mentioned above restored correct touchpad operation with kernel 4.2.0. It seems that the Latitude D600 is different than other Dell models.

Larry


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