On Wed, Dec 03, 2014 at 11:58:11AM -0800, Dmitry Torokhov wrote: > Hi Karl, > > On Tue, Dec 02, 2014 at 12:17:40AM -0500, Karl Dahlke wrote: > > From: Karl Dahlke <eklhad@xxxxxxxxx> > > > > Add clicks, tones, and tone sequences to the pc speaker. > > > > The speaker driver can play a tone at a specified frequency, > > or the standard control G bell, > > which is a special case of TONE at 1000 hz 0.1 seconds. > > Add kd_mkpulse() to generate a soft click. > > This is introduced to support accessibility modules and adapters in the future. > > It is a means to an end. > > With this function in place, a module can easily provide soft clicks, > > i.e. audible feedback, whenever a key is depressed, > > or when that keystroke is echoed on screen. > > This allows a blind user, for example, to have rapid feedback while typing, > > even if he is, at the same time, listening to text that is already on screen. > > It is faster and more convenient than having characters echoed verbally. > > And it works all the time, even if speech or braille is not working > > for whatever reason. > > > > Also add the function kd_mknotes, > > which plays a series of tones in the background. > > Of course this can already be done with kd_mksound and timers, > > but why should everyone reinvent the wheel? > > It is better to write the function once, properly, in the kernel, > > and let modules use it thereafter. > > Again, this is a means to an end. > > Accessibility modules can generate rapid sequences of notes > > to indicate various conditions, sometimes error conditions, > > especially if speech or braille is not working. > > These notes may be the only feedback the user has to diagnose the problem. > > This may be useful to other developers in other situations as well. > > > > Finally add kd_mksteps to run something like a chromatic scale, > > from one frequency to another in specified steps. > > The half-tone scale, with a step of 6%, starting at middle C, is approximately > > kd_mksteps(260, 530, 6, 150); > > I have exactly the same response as a year earlier: > > "I do not think it is a good idea to add SND_PULSE as it can be easily > implemented by SND_TONE with the additional benefit that parameters of > the click can be adjusted. Also, if clicking is done elsewhere, it would > work with other speaker drivers besides pcspkr. SND_PULSE would make sense in case (and only in case) there are devices that can emit that kind of sound without being able to implement SND_TONE. This is the reason why SND_CLICK and SND_BELL exist. And, by the way, the implementation of SND_PULSE in the patch is quite horrible. If a variable-width pulse makes sense at all (based on the speaker dynamics, a long enough pause will be two clicks and high power consumption inbetween), it should be done by programming the i8253 to do a one-shot timer rather than bitbanging it. > [re kd_mknotes] Can it be put into a library instead? Especially given > David's work on trying to push the VT code out of the kernel. Also, what > if you want clicks to go through sound card and not the speaker > interface?" > > In other words, I'd rather have it all be done in userpsace by a daemon > that listens to all keystrokes and emits notes or clicks or something > else via whatever sound device is present on the system, be it a PC > speaker, SPARC speaker, a sound card, or maybe something else. > > Thanks. > > -- > Dmitry > -- Vojtech Pavlik Director SUSE Labs -- 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
