[RFC 5/5] pwm: pwm-omap-dmtimer: Add capture functionality

[tony@atomide.com (Tony Lindgren)]

* Ladislav Michl <ladis@linux-mips.org> [180108 22:09]:
> On Mon, Jan 08, 2018 at 01:59:31PM -0800, Tony Lindgren wrote:
> > * Ladislav Michl <ladis@linux-mips.org> [180108 15:46]:
> > > Here it seems hardware can capture both edges, but I do not see a way
> > > how to tell it I want start from either low to high or high to low
> > > transition. Clues?
> > 
> > At least dm3730 TRM documents TCM bits [9:8] for TCLR, but you
> > probably know that already..
> > 
> > If you're having hard time getting things starting, maybe something
> > like this helps:
> > 
> > stop timer in TCLR register
> > configure timer in TCLR
> > write some value to TLDR, maybe 0?
> > set ST bit in TCLR to start
> 
> Let me clarify it a bit more. I have no problem starting timer and capture
> events. I just didn't find a way how to tell hardware I want to start
> with for example rising edge, so rising edge goes to TCAR1 and failing edge
> to TCAR2. Substracting those gives pulse width.

Oh I see, yeah that would be cool :) Maybe you can first configure
an interrupt to trigger on rising edge, then configure things for
falling edge, then subtract..

Regards,

Tony