Re: [PATCH] rtc: snvs: make sure clock is enabled for interrupt handle
On 11/01/2019 07:09:02+, Anson Huang wrote: > During system suspend, the SNVS RTC's clock will be disabled in > noirq suspend phase, but SNVS RTC's alarm interrupt could still > arrive, system will hang if SNVS RTC driver tries to access register > without clock enabled, this patch fixes the issue of this scenario. > > Signed-off-by: Anson Huang > --- > drivers/rtc/rtc-snvs.c | 6 ++ > 1 file changed, 6 insertions(+) Applied, thanks. -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
RE: [PATCH] rtc: snvs: make sure clock is enabled for interrupt handle
Hi, Alexandre Best Regards! Anson Huang > -Original Message- > From: Alexandre Belloni [mailto:alexandre.bell...@bootlin.com] > Sent: 2019年1月11日 22:32 > To: Anson Huang > Cc: a.zu...@towertech.it; linux-...@vger.kernel.org; > linux-kernel@vger.kernel.org; dl-linux-imx > Subject: Re: [PATCH] rtc: snvs: make sure clock is enabled for interrupt > handle > > Hi, > > On 11/01/2019 07:09:02+, Anson Huang wrote: > > During system suspend, the SNVS RTC's clock will be disabled in noirq > > suspend phase, but SNVS RTC's alarm interrupt could still arrive, > > system will hang if SNVS RTC driver tries to access register without > > clock enabled, this patch fixes the issue of this scenario. > > > > Are you sure this is the real issue? I don't think the handler can be called > before the resume_noirq callback. Isn't the issue that your clock driver has > not > yet resumed by the time you call the rtc driver resume_noirq callback ? Yes, since the RTC alarm is wakeup source, it is NOT being disabled during suspend flow at all, after rtc drvier's noirq suspend callback is being called, rtc clock is disabled in this callback, rtc alarm could arrive at this point then ARM IRQ is NOT disabled yet, so rtc irq handler will be called, so the handler will access RTC register with RTC clock disabled and cause system hang. The point is RTC clock is disabled in noirq suspend callback. > > > Signed-off-by: Anson Huang > > --- > > drivers/rtc/rtc-snvs.c | 6 ++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/drivers/rtc/rtc-snvs.c b/drivers/rtc/rtc-snvs.c index > > b2483a7..0b9eff1 100644 > > --- a/drivers/rtc/rtc-snvs.c > > +++ b/drivers/rtc/rtc-snvs.c > > @@ -239,6 +239,9 @@ static irqreturn_t snvs_rtc_irq_handler(int irq, void > *dev_id) > > u32 lpsr; > > u32 events = 0; > > > > + if (data->clk) > > + clk_enable(data->clk); > > + > > Anyway, won't that need a clk_prepare_enable because it has been > clk_disable_unprepare in suspend_noirq? And this is something you can not > do in atomic context Yes, but the prepare/unprepared can NOT be called in atomic context, since the SNVS RTC clock on i.MX SoC is always from a clock source without prepare/unprepared needed, such as from ipg or OSC etc., so just doing enable/disable is good enough for it. Anson. > > -- > Alexandre Belloni, Bootlin > Embedded Linux and Kernel engineering > https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbootl > in.comdata=02%7C01%7Canson.huang%40nxp.com%7Ca90608144e90 > 494a6f3608d677d1818a%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C > 0%7C636828139042107931sdata=oX%2Bqnj4X3nS%2Ba88otedt9WyIy > VhBNVl5eixVWeV44TA%3Dreserved=0
Re: [PATCH] rtc: snvs: make sure clock is enabled for interrupt handle
Hi, On 11/01/2019 07:09:02+, Anson Huang wrote: > During system suspend, the SNVS RTC's clock will be disabled in > noirq suspend phase, but SNVS RTC's alarm interrupt could still > arrive, system will hang if SNVS RTC driver tries to access register > without clock enabled, this patch fixes the issue of this scenario. > Are you sure this is the real issue? I don't think the handler can be called before the resume_noirq callback. Isn't the issue that your clock driver has not yet resumed by the time you call the rtc driver resume_noirq callback ? > Signed-off-by: Anson Huang > --- > drivers/rtc/rtc-snvs.c | 6 ++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/rtc/rtc-snvs.c b/drivers/rtc/rtc-snvs.c > index b2483a7..0b9eff1 100644 > --- a/drivers/rtc/rtc-snvs.c > +++ b/drivers/rtc/rtc-snvs.c > @@ -239,6 +239,9 @@ static irqreturn_t snvs_rtc_irq_handler(int irq, void > *dev_id) > u32 lpsr; > u32 events = 0; > > + if (data->clk) > + clk_enable(data->clk); > + Anyway, won't that need a clk_prepare_enable because it has been clk_disable_unprepare in suspend_noirq? And this is something you can not do in atomic context -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
[PATCH] rtc: snvs: make sure clock is enabled for interrupt handle
During system suspend, the SNVS RTC's clock will be disabled in
noirq suspend phase, but SNVS RTC's alarm interrupt could still
arrive, system will hang if SNVS RTC driver tries to access register
without clock enabled, this patch fixes the issue of this scenario.
Signed-off-by: Anson Huang
---
drivers/rtc/rtc-snvs.c | 6 ++
1 file changed, 6 insertions(+)
diff --git a/drivers/rtc/rtc-snvs.c b/drivers/rtc/rtc-snvs.c
index b2483a7..0b9eff1 100644
--- a/drivers/rtc/rtc-snvs.c
+++ b/drivers/rtc/rtc-snvs.c
@@ -239,6 +239,9 @@ static irqreturn_t snvs_rtc_irq_handler(int irq, void
*dev_id)
u32 lpsr;
u32 events = 0;
+ if (data->clk)
+ clk_enable(data->clk);
+
regmap_read(data->regmap, data->offset + SNVS_LPSR, );
if (lpsr & SNVS_LPSR_LPTA) {
@@ -253,6 +256,9 @@ static irqreturn_t snvs_rtc_irq_handler(int irq, void
*dev_id)
/* clear interrupt status */
regmap_write(data->regmap, data->offset + SNVS_LPSR, lpsr);
+ if (data->clk)
+ clk_disable(data->clk);
+
return events ? IRQ_HANDLED : IRQ_NONE;
}
--
2.7.4
