Hi Mark, On Mon, Jun 30, 2025 at 05:42:45AM +0900, Mark Pearson wrote: > Hi Dmitry, > > On Fri, Jun 27, 2025, at 2:14 PM, Dmitry Torokhov wrote: > > Hi Vishnu, > > > > On Fri, Jun 20, 2025 at 09:42:08AM +0900, Vishnu Sankar wrote: > >> Newer ThinkPads have a doubletap feature that needs to be turned > >> ON/OFF via the trackpoint registers. > >> Systems released from 2023 have doubletap disabled by default and > >> need the feature enabling to be useful. > >> > >> This patch introduces support for exposing and controlling the > >> trackpoint doubletap feature via a sysfs attribute. > >> /sys/devices/platform/thinkpad_acpi/tp_doubletap > >> This can be toggled by an "enable" or a "disable". > >> > >> With this implemented we can remove the masking of events, and rely on > >> HW control instead, when the feature is disabled. > >> > >> Note - Early Thinkpads (pre 2015) used the same register for hysteris > >> control, Check the FW IDs to make sure these are not affected. > >> > >> trackpoint.h is moved to linux/input/. > > > > No, please keep everything private to trackpoint.c and do not involve > > thinkpad_acpi driver. By doing so you are introducing unwanted > > dependencies (for both module loading, driver initialization, and > > operation) and unsafe use of non-owned pointers/dangling pointers, etc. > > > > Do you have recommendations on how to handle this case then? > > This is a Thinkpad specific feature and hence the logic for involving > thinkpad_acpi. There are Thinkpad hotkeys that will enable/disable the > trackpoint doubletap feature - so there is some linkage. I'm not sure > how to avoid that. > > Is there a cleaner way to do this that you'd recommend we look at > using? It's a feature (albeit a minor one) on the laptops that we'd > like to make available to Linux users.
I believe if you define the doubletap as an attribute (see TRACKPOINT_INT_ATTR or TRACKPOINT_BIT_ATTR in drivers/input/mouse/trackpoint.c) then whatever process is handling the hot keys switching this function on or off should be able to toggle the behavior. The difference is that it will have to locate trackpoint node in /sys/bus/serio/devices/* (or maybe scan /sys/devices/platform/i8042/serio*) instead of expecting the attributes be atached to thinkpad_acpi instance. You just don't want to have one driver directly peeking into another, because then it starts breaking if you unbind or force use of a different protocol, etc. Thanks. -- Dmitry _______________________________________________ ibm-acpi-devel mailing list ibm-acpi-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/ibm-acpi-devel
