hi dmitry -- have you had a chance to think any more about this? i'm open to suggestions on implementation detail, but i think that a full reset of the device won't really work, because of the time it adds to the recalibration. paul andres wrote: > On Wed, 03 Jun 2009 23:58:33 -0400 > Paul Fox <pgf@xxxxxxxxxx> wrote: > > > dmitry wrote: > > > Hi Paul, > > > > > > On Tuesday 02 June 2009 12:47:59 pgf@xxxxxxxxxx wrote: > > > > The OLPC XO laptop incorporates a combination touchpad/tablet > > > > device which unfortunately requires frequent recalibration. The > > > > driver will force this automatically when various suspicious > > > > behaviors are observed, and the user can recalibrate manually > > > > (with a special keyboard sequence). There's currently no way, > > > > however, for an external program to cause recalibration. > > > > > > > > This patch creates a new node in /sys which, when written with > > > > '1', will force a touchpad recalibration. No other writes (or > > > > reads) of this node are supported. > > > > > > > > > > > > > Instead of creating a new sysfs attribute maybe we should make > > > the touchpad recalibrate upon resume (reconnect)? Userspace can > > > already request reconnect via sysfs. > > > > dmitry -- thanks for the suggestion. > > > > i took a look, and tried it. the problem is that doing a full > > reset of the touchpad takes quite a long time -- 1.1 or 1.2 > > seconds. recalibration deprives the user of their touchpad for > > long enough as it is -- i don't think we can afford that time. > > (remember that this is a workaround for bad hardware -- the XO > > no longer uses this touchpad at least partly due to this very > > issue, but there are enough in use that we're still trying to > > improve things.) > > > > I do like the idea of having a sysfs trigger for recalibrations. We've > never been successful in having the kernel driver handle recalibrations > seamlessly. Perhaps touchpad hardware screwups would be easier to > detect in userspace, given a daemon that can keep a history of the last > N touchpad coordinates? =--------------------- paul fox, pgf@xxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
