Re: how fast can you run a hrtimer?

[afzal mohammed <afzal.mohd.ma@gmail.com>]

Hi

> On Fri, Aug 18, 2017 at 8:35 AM, Cliff Brake <cliff.brake@gmail.com> wrote:

> > I have an application where we need to tweak a PWM setting every 10uS.
> > My impression is this is beyond the capabilities of linux+rt, but want
> > to verify I'm not missing anything before we add an external
> > microcontroller to handle this.
> >
> > I've run some experiments on a i.MX6UL with v4.1+rt, and observe
> > delays of ~50us when toggling a GPIO in a Linux driver using a
> > hrtimer.

On Fri, Aug 18, 2017 at 10:34:19AM -0400, Cliff Brake wrote:
> After a suggestion of using a NMI and a bit of research, it seems
> something like the following article is the probably a reasonable
> approach:
> 
> http://free-electrons.com/blog/fiq-handlers-in-the-arm-linux-kernel/

If a PWM IP is present on the chip, won't updating the PWM compare
registers within 10us (PWM @100KHz) achieve the required ?, toggling
delay & jitter shouldn't be a worry here, right ? (assuming PWM
compare registers can be updated every 10us using hrtimers)

afzal