From mboxrd@z Thu Jan 1 00:00:00 1970 From: daniel.lezcano@linaro.org (Daniel Lezcano) Date: Thu, 28 Nov 2013 12:55:38 +0100 Subject: [PATCH v2 4/9] clocksource/cadence_ttc: Use enable/disable_irq In-Reply-To: <1385514296-26702-5-git-send-email-soren.brinkmann@xilinx.com> References: <1385514296-26702-1-git-send-email-soren.brinkmann@xilinx.com> <1385514296-26702-5-git-send-email-soren.brinkmann@xilinx.com> Message-ID: <52972F3A.9090103@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 11/27/2013 02:04 AM, Soren Brinkmann wrote: > To ensure that the timer interrupt is properly enabled/disabled across > the whole CPU cluster use enable/disable_irq() instead of > local_irq_disable(). > > Signed-off-by: Soren Brinkmann > --- > drivers/clocksource/cadence_ttc_timer.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/drivers/clocksource/cadence_ttc_timer.c b/drivers/clocksource/cadence_ttc_timer.c > index a92350b55d32..246d018d1e63 100644 > --- a/drivers/clocksource/cadence_ttc_timer.c > +++ b/drivers/clocksource/cadence_ttc_timer.c > @@ -322,18 +322,16 @@ static int ttc_rate_change_clockevent_cb(struct notifier_block *nb, > switch (event) { > case POST_RATE_CHANGE: > { > - unsigned long flags; > - > /* > * clockevents_update_freq should be called with IRQ disabled on > * the CPU the timer provides events for. The timer we use is > * common to both CPUs, not sure if we need to run on both > * cores. > */ > - local_irq_save(flags); > + disable_irq(ttcce->ce.irq); > clockevents_update_freq(&ttcce->ce, > ndata->new_rate / PRESCALE); > - local_irq_restore(flags); > + enable_irq(ttcce->ce.irq); > > /* update cached frequency */ > ttc->freq = ndata->new_rate; > I am worried about the 'disable_irq' function calling 'synchronize_irq'. Isn't possible to deadlock with the ondemand cpufreq governor ? I added Viresh in Cc, he knows better than me the code path. -- Linaro.org ? Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog