On 09/12/2016 04:41 PM, David Rivshin wrote: > On Sat, 10 Sep 2016 15:48:28 +0200 > Neil Armstrong <narmstrong@xxxxxxxxxxxx> wrote: > >> Le 10/09/2016 05:17, Matthijs van Duin a écrit : >>> On Mon, Sep 05, 2016 at 11:16:38AM +0200, H. Nikolaus Schaller wrote: >>>> This helps to get 100% intensity closer to "always on". [...] >>> } >>> >>> At the time I used a scope to check the exact behaviour of dmtimer pwm >>> on a dm814x. My notes mention (when pwm enabled): >>> match < reload output on continuous >>> match == reload output on 1 cycle, off period-1 cycles >>> match == -2 output on period-1 cycles, off 1 cycle >>> match == -1 output freezes >>> >>> Hope this helps >> >> Hi, >> >> I think these corner cases should definitely be handled in the dmtimer driver. > > Do you mean to modify the dmtimer driver itself, or the pwm-omap-dmtimer > driver? > > IIRC from the last time I was in the pwm-omap-dmtimer driver, it seemed to > me that the 0% and 100% cases could/should be handled as simple special > cases there. I think the dmtimer driver itself has the necessary API to the > HW, but I'd need to re-familiarize myself with it to remember the details > of what I was thinking. > > Actually, I did mention some thoughts on this a previous thread where > Adam Ford was using pwm-omap-dmtimer for a backlight: > http://www.spinics.net/lists/linux-omap/msg126006.html > So it may be as simple as using PWM_OMAP_DMTIMER_TRIGGER_NONE and passing > def_on according to whether 0 or 100% duty were requested (and polarity). Yes it's exactly what I was talking about. > > >> >> I'll try to post a fix to handle these, thanks for the original code dump. >> >>> >>> Matthijs >>> >> >> Neil Thanks, Neil -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
