Messages in this thread | | | Date | Fri, 17 Nov 2006 09:16:05 -0500 | From | "Dmitry Torokhov" <> | Subject | Re: [PATCH] usb: generic calibration support |
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Hi,
On 11/17/06, Holger Schurig <hs4233@mail.mn-solutions.de> wrote: > > sorry, but i have to give you a big NACK on that one: > > Hehe, I actually anticipated this NACK :-) > > > - no more modparam: it should be per-device sysfs attributes > > (swap_xy is basically only for touchkitusb compatibility and > > shoud be converted to per-device sysfs attribute as well. i > > just never got to do it) > > That would be okay for me. >
Actually I think having module parameter is OK as long as we have comlementing device attribute. Then user has an option to either specify default value for the parameter at load/boot time or fiddle with an individual device.
> > - calibration can be handled in userspace just fine > > Yes it can, and that is the most convinging argument against my > patch. > > However, user-space calibration often sucks. For example, in X11 > the calibration values are stored in /etc/X11/xorg.conf, so a > calibration program has to parse & write that file. And I've > seen binary-only-calibration programs from vendors > use /etc/X11/XF86Config, which doesn't exist here. Anyway, once > you've calibrated you have to restart X-Windows, so you need to > terminate all running X applications just because of a silly > re-calibration. Not nice. >
I believe tslib handles this.
> A calibration at kernel level (may it be input level or driver > level) doesn't have this problem. I can make the level > persistent via udev, modules.conf or other means. Even when I > have a frame-buffer based calibration utility, the calibration > would be OK for X11 or GTK/DirectFB as well. > > For me, this speaks against "Calibration is purely a user-space > problem". > > > - even for in-kernel it's in the wrong place. there are other > > devices that report raw absolute data...so it would belong to > > the input layer > > Suppose I have a graphics tabled and a touchscreen connected at > the same time. Can I distinguish this easily at the input layer > level? > > I can very easily distinguish this at the device driver level. > After all, the individual calibration parameters are a property > of this individual device. >
Yes, but evdev is the interface between input layer and userspace. If we ever implement in-kernel calibration I think we'll add recalibrate() method to input device structure and have EVIOCSABS ioctl handler call it. But I'd look at tslib first. I believe Qt, Xserver, etc support it.
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