Messages in this thread | | | Date | Wed, 21 Sep 2016 16:34:37 +0200 | From | Daniel Lezcano <> | Subject | Re: [PATCH v2] clocksource/fsl: Fix errata A-007728 for flextimer |
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On Sun, Sep 18, 2016 at 02:46:01PM +0800, Meng Yi wrote: > If the FTM counter reaches the FTM_MOD value between the reading of the > TOF bit and the writing of 0 to the TOF bit, the process of clearing the > TOF bit does not work as expected when FTMx_CONF[NUMTOF] != 0 and the > current TOF count is less than FTMx_CONF[NUMTOF]. If the above condition > is met, the TOF bit remains set. If the TOF interrupt is enabled > (FTMx_SC[TOIE] = 1), the TOF interrupt also remains asserted. > > Above is the errata discription > > The workaround is clearing TOF bit until it is cleaned(FTM counter doesn't > always reache the FTM_MOD anyway),which may cost some cycles. > > Signed-off-by: Meng Yi <meng.yi@nxp.com> > --- > Change in V2: > -add timeout into IRQ context(suggested by Alexander) > --- > drivers/clocksource/fsl_ftm_timer.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/drivers/clocksource/fsl_ftm_timer.c b/drivers/clocksource/fsl_ftm_timer.c > index 738515b..86f9186 100644 > --- a/drivers/clocksource/fsl_ftm_timer.c > +++ b/drivers/clocksource/fsl_ftm_timer.c > @@ -83,11 +83,13 @@ static inline void ftm_counter_disable(void __iomem *base) > > static inline void ftm_irq_acknowledge(void __iomem *base) > { > - u32 val; > + unsigned long timeout = jiffies + msecs_to_jiffies(100);
Do you expect the jiffies to be updated when we are in the timer irq handler ?
> - val = ftm_readl(base + FTM_SC); > - val &= ~FTM_SC_TOF; > - ftm_writel(val, base + FTM_SC); > + /*read and clean the FTM_SC_TOF bit until its cleared*/ > + while ((FTM_SC_TOF & ftm_readl(base + FTM_SC)) && > + time_before(jiffies, timeout)) > + ftm_writel(ftm_readl(base + FTM_SC) & (~FTM_SC_TOF), > + base + FTM_SC); > } > > static inline void ftm_irq_enable(void __iomem *base) > -- > 2.1.0.27.g96db324 >
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