linux-kernel - Re: [4.12 regression] Thinkpad X250 Touchpad and Trackpoint not recognized anymore; commit e839ffa: "Input: synaptics

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Message-ID: <20170520095950.GB6808@mail.corp.redhat.com>
Date:   Sat, 20 May 2017 11:59:50 +0200
From:   Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:     Pascal Wichmann <pascal.wichmann@...w.de>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [4.12 regression] Thinkpad X250 Touchpad and Trackpoint not
 recognized anymore; commit e839ffa: "Input: synaptics - add support for
 Intertouch devices"

Hi,

On May 20 2017 or thereabouts, Pascal Wichmann wrote:
> > Looks like you running your patched kernel?
> That's right.
> 
> 
> >>> CONFIG_RMI4_CORE=m
> >>> CONFIG_RMI4_I2C=m
> >>> CONFIG_RMI4_SPI=m
> >>> # CONFIG_RMI4_SMB is not set
> >
> > This is your issue I believe.
> 
> Indeed, enabling that configuration solves that issue.
> 
> However, I think it is quite unintuitive that a module (psmouse) chooses
> a default mode which requires another driver which is not necessarily
> included; though it would probably be not a very clean solution to
> explicitly check that as well.
> 
> Is this behaviour, that one module requires another without
> communicating that clearly, wanted?
> 

I can see 3 solutions:
1. Have PS2_SMBUS depending on RMI_SMBUS (and ELAN_I2C, and others when
   required)
2. Have PS2_SMBUS selecting RMI_SMBUS (and the others when time comes)
3. Changing the default value of synaptics_intertouch to
   SYNAPTICS_INTERTOUCH_OFF when RMI_SMBUS is not set

Solution 3. might be interesting because it doesn't prevent users to
compile the module on the side and is Synaptics only.

Dmitry, any comments?

Cheers,
Benjamin

> Thanks,
> Pascal
> 
>