Alexander: On Thu, Mar 10, 2011 at 1:36 AM, Alexander Stein <alexander.stein@xxxxxxxxxxxxxxxxxxxxx> wrote: > As far as I can see, the previosly support for pwm_channel_handler has been > dropped. The new API doesn't support such things. > What do you think about adding this? It might be important to change the PWM > setup after a specific amount of time. Reviewers of the implementation noted some race conditions, and had additional objections to the implementation. They suggested that I reimplement channel handlers using genirq. Since the pwm_channel_handler implementation was broken, I removed it from the implementation. I haven't yet started on the genirq-based approach, for two reasons: I'm trying to get everything else into mainline; and, I'm not quite sure yet how to stitch genirq together with "genpwm". There is a larger question, however, that I would like to hear your answer on since you seem interested in the subject: are end-of-period callbacks really necessary? If you are trying to "ramp" a PWM signal from a low duty cycle to a high one, would an hrtimer suffice? Assuming that a PWM device driver can implement duty cycle and/or period changes without glitches, is it really necessary to stay so tightly synchronized to the PWM signal the way that an end-of-period callback would allow? In my work, I haven't encountered a need for end-of-period callbacks when doing mere PWM signal generation (though the topic is very important when counting pulses, which I'm considering a different implementation/API for). I don't know if my experience is comprehensive, however. Would love to hear your opinion. b.g. -- Bill Gatliff bgat@xxxxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
