From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Lezcano Subject: Re: [PATCH v2 5/9] clocksource/cadence_ttc: Adjust interval in clock notifier Date: Thu, 12 Dec 2013 13:15:38 +0100 Message-ID: <52A9A8EA.3080609@linaro.org> References: <1385514296-26702-1-git-send-email-soren.brinkmann@xilinx.com> <1385514296-26702-6-git-send-email-soren.brinkmann@xilinx.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1385514296-26702-6-git-send-email-soren.brinkmann-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Soren Brinkmann , Rob Herring , Pawel Moll , Mark Rutland , Stephen Warren , Ian Campbell , Russell King , Michal Simek , Thomas Gleixner Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org On 11/27/2013 02:04 AM, Soren Brinkmann wrote: > The clockevent has to be reprogrammed if the timer's input > clock frequency changes and the timer is in periodic mode, in order t= o > maintain the correct timer interval. > > Signed-off-by: Soren Brinkmann > --- > v2: > - adjust the timer interval while the timer interrupt is disabled > --- > drivers/clocksource/cadence_ttc_timer.c | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/drivers/clocksource/cadence_ttc_timer.c b/drivers/clocks= ource/cadence_ttc_timer.c > index 246d018d1e63..77517675653e 100644 > --- a/drivers/clocksource/cadence_ttc_timer.c > +++ b/drivers/clocksource/cadence_ttc_timer.c > @@ -322,6 +322,9 @@ static int ttc_rate_change_clockevent_cb(struct n= otifier_block *nb, > switch (event) { > case POST_RATE_CHANGE: > { > + /* update cached frequency */ > + ttc->freq =3D ndata->new_rate; > + > /* > * clockevents_update_freq should be called with IRQ disabled on > * the CPU the timer provides events for. The timer we use is > @@ -329,12 +332,15 @@ static int ttc_rate_change_clockevent_cb(struct= notifier_block *nb, > * cores. > */ > disable_irq(ttcce->ce.irq); > + > clockevents_update_freq(&ttcce->ce, > ndata->new_rate / PRESCALE); > - enable_irq(ttcce->ce.irq); > > - /* update cached frequency */ > - ttc->freq =3D ndata->new_rate; > + if (ttcce->ce.mode =3D=3D CLOCK_EVT_MODE_PERIODIC) > + ttc_set_interval(ttc, DIV_ROUND_CLOSEST(ttc->freq, > + PRESCALE * HZ)); > + > + enable_irq(ttcce->ce.irq); > > /* fall through */ > } When looking at the smp_twd.c, there is a similar need. There are a couple of notifier used on for cpufreq and one for clock=20 rate change. Wouldn't make sense to add the notifier calls and registration in the=20 time framework and add the callbacks in the dev ops ? The switch would=20 be in the timer framework and perhaps the irq disabling may be easier t= o=20 deal with ? --=20 Linaro.org =E2=94=82 Open source software fo= r ARM SoCs =46ollow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe devicetree" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html