On Wed, Oct 16, 2013 at 06:21:12PM -0500, Benjamin Herrenschmidt wrote: > On Wed, 2013-10-16 at 11:04 +0200, Hendrik Brueckner wrote: > > Indeed, two callbacks change the DTR line. The main difference is that > > tiocmget/tiocmset can be called from user space by ioctl. That's not the case > > for the dtr_cts callback. Also, tiocmget/tiocmset provide more flags that can > > be changed (ST, SR, CTS, CD, RNG, RI, ...) > > > > Assume we would like to unify them have a single callback to change DTR, then > > we have to take care of these differences. So the question to you now is > > whether you plan for a) other modem flags to be changed and b) if changing the > > DTR line (or other control flags) through an ioctl? > > > > Depending on your results, I could work on sth that helps us both and reduces > > the callbacks. > > Can we not just have the users of dtr_cts just call the backend's tiocmset ? That's possible. The only concern is that the tiocmset() callback could be triggered from within the hvc_console() layer as well as from user space via ioctl. For the hvc_iucv driver, I do not want to introduce this ioctl. One option would be to add parameter to the hvc_callbacks that indicate the origin so that a backend could filter. > If they need to filter or clamp bits, we could handle all that in hvc_console > by caching the user intended value and passing a cooked value down to the backend.. Sure the hvc_console layer could do as much as possible. > > None of that is urgent or anything, it's just odd and would be nice to cleanup. Thanks and kind regards, Hendrik -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
