On Tue, Aug 16, 2016 at 08:40:08PM +0000, Zhengyu Shen wrote: > > > > > + hrtimer_start(&pmu_mmdc->hrtimer, mmdc_timer_period(), > > > > > + HRTIMER_MODE_REL_PINNED); > > > > > > > > Why is a hrtimer necessary? Is this just copy-pasted from CCN, or do > > > > you have similar HW issues? > > > > > > > > Is there no overflow interrupt? > > > > > > When overflow occurs, a register bit is set to one. There is no > > > overflow interrupt which is why the timer is needed. > > > > I see. Please have add comment in the driver explaining this, so that this > > is > > obvious. > > > > Does the counter itself wrap and continue counting, or does it saturate? > > > > How have you tuned your polling period so as to avoid missing events in the > > case of an overflow? > > > > Thanks, > > Mark. > The counter wraps around once every ten seconds for total-cycles (which is > the > Fastest increasing counter). Polling is done every one second just to be safe.
Ok. It would be worth noting this with a comment next to either the hrtimer handler or registration thereof. I assume that on overflow the counter wraps rather than saturating? Thanks, Mark.
