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    SubjectRe: [PATCH] Input: evdev - use monotonic clock for event timestamps
    On 10/05/2011 10:23 AM, Henrik Rydberg wrote:
    >> I understand your concern about breaking random drivers, and am hoping
    >> that someon on this list could indicate whether this is a real concern
    >> or not. To get a better feeling for possible regressions, I checked
    >> xf86-input-evdev & -synaptics, and neither uses the evdev timestamp in
    >> their current incarnations. Any idea what else might be a good place
    >> to check?
    >
    > The input system is used for all sorts of events - switches, for
    > instance. The point is that it is nearly impossible to know if
    > something will break or not, hence the reluctance to modify interfaces.
    >
    >> One option is to make the evdev timestamp clock source a per-driver
    >> configuration option (controllable from userspace?). This sounds like
    >> it is doable, but would be significantly more complicated.
    >>
    >> Another option would be to timestamp with monotonicraw + boottime +
    >> sleeptime. This would be approximately wall clock time, but without
    >> ntp and slew adjustments. But, I fear this would just make the rare
    >> driver issue less obvious, since it would only become obvious when the
    >> two clock sources started drifting apart.
    >
    > I agree, the problem is not really solvable. Dmitry?

    We could put it into the -next tree early on in the cycle, and then it
    will be in -next for a cycle and in Linus' tree for the real dev cycle.
    By that time we would hope any issues would have emerged.

    I'm not sure if that is a responsible approach. I agree that the change
    would be good, but how sure would we be that nothing would break based
    only on testing in development trees?

    My personal thoughts are that I doubt it would cause issues. Based on
    that gut feel, I would say that this approach is reasonable. However,
    I'm just one voice in all this :).

    -- Chase


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