[systemd-devel] [RFC PATCH] udev: add an "abs-override" builtin to override EV_ABS data
dh.herrmann at gmail.com
Thu Mar 19 05:54:46 PDT 2015
On Thu, Mar 19, 2015 at 10:52 AM, Peter Hutterer
<peter.hutterer at who-t.net> wrote:
> This builtin parses properties in the form
The concept sounds good. hwdb is definitely the place to put this,
rather than static kernel fixups.
> and applies them to the kernel device. Future processes that open that device
> will see the updated EV_ABS range.
> This is particularly useful for touchpads that don't provide a resolution in
> the kernel driver but can be fixed up through hwdb entries (e.g. bcm5974).
> All values in the property are optional, e.g. a string of "::45" is valid to
> set the resolution to 45.
> The order intentionally orders resolution before fuzz and flat despite it
> being the last element in the absinfo struct. The use-case for setting
> fuzz/flat is almost non-existent, resolution is probably the most common case
> we'll need.
If a field is left empty, should it take the kernel-provided values?
This way, you could just order it logically and leave stuff you don't
wanna change empty.
> This is just an RFC for now, a couple of questions remain:
> * we need this for touchpads, but this seems something that could be more
> generic and have it's own ruleset, possibly depending on ID_INPUT_TOUCH*
> or so
> * input_id is already called and opens the device, we could merge this in
Don't get confused by the name of this builtin. It's legacy. We should
probably also merge 'keyboard' into it.
Talking about the 'keyboard' builtin: why not merge both? They serve
the same purpose, fixing wrong kernel mapping/data. You could even
rename the prefix to "evdev" ('input' is reserved..), and then put
both into the same file. You could re-use the matching we have in
place for keyboards. I think it would work well enough for all other
input-devices, too. It uses the input-modalias, and device-name+dmi as
fallback. Ok, the "atkbd:" is special to keyboards, but just ignore
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