diff mbox series

[v5,2/2] rtc: omap: Cut down the shutdown time from 2 seconds to 1 sec

Message ID 1532497882-8828-2-git-send-email-j-keerthy@ti.com (mailing list archive)
State New, archived
Headers show
Series [v5,1/2] rtc: omap: use of_device_is_system_power_controller function | expand

Commit Message

J, KEERTHY July 25, 2018, 5:51 a.m. UTC
Cut down the shutdown time from 2 seconds to 1 sec. In case of roll
over try again.

Signed-off-by: Keerthy <j-keerthy@ti.com>
---

Changes in v5:

  * Added an additional check to see if ALARM2 status is not set
    before retrying.
  * Cleaned up comments
  * Also reduced mdelay to 1S lesser as per this commit

 drivers/rtc/rtc-omap.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

Comments

Alexandre Belloni July 25, 2018, 9:30 a.m. UTC | #1
Hi,

On 25/07/2018 11:21:22+0530, Keerthy wrote:
> Cut down the shutdown time from 2 seconds to 1 sec. In case of roll
> over try again.
> 
> Signed-off-by: Keerthy <j-keerthy@ti.com>
> ---
> 
> Changes in v5:
> 
>   * Added an additional check to see if ALARM2 status is not set
>     before retrying.
>   * Cleaned up comments
>   * Also reduced mdelay to 1S lesser as per this commit
> 
>  drivers/rtc/rtc-omap.c | 28 ++++++++++++++++++----------
>  1 file changed, 18 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
> index 44ff4cc..caa6da6 100644
> --- a/drivers/rtc/rtc-omap.c
> +++ b/drivers/rtc/rtc-omap.c
> @@ -421,12 +421,6 @@ static int omap_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
>   * The RTC can be used to control an external PMIC via the pmic_power_en pin,
>   * which can be configured to transition to OFF on ALARM2 events.
>   *
> - * Notes:
> - * The two-second alarm offset is the shortest offset possible as the alarm
> - * registers must be set before the next timer update and the offset
> - * calculation is too heavy for everything to be done within a single access
> - * period (~15 us).
> - *
>   * Called with local interrupts disabled.
>   */
>  static void omap_rtc_power_off(void)
> @@ -435,17 +429,20 @@ static void omap_rtc_power_off(void)
>  	struct rtc_time tm;
>  	unsigned long now;
>  	u32 val;
> +	int seconds;
>  
>  	rtc->type->unlock(rtc);
>  	/* enable pmic_power_en control */
>  	val = rtc_readl(rtc, OMAP_RTC_PMIC_REG);
>  	rtc_writel(rtc, OMAP_RTC_PMIC_REG, val | OMAP_RTC_PMIC_POWER_EN_EN);
>  
> -	/* set alarm two seconds from now */
> +again:
> +	/* set alarm one second from now */
>  	omap_rtc_read_time_raw(rtc, &tm);
> +	seconds = tm.tm_sec;
>  	bcd2tm(&tm);
>  	rtc_tm_to_time(&tm, &now);
> -	rtc_time_to_tm(now + 2, &tm);
> +	rtc_time_to_tm(now + 1, &tm);
>  
>  	if (tm2bcd(&tm) < 0) {
>  		dev_err(&rtc->rtc->dev, "power off failed\n");
> @@ -470,14 +467,25 @@ static void omap_rtc_power_off(void)
>  	val = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
>  	rtc_writel(rtc, OMAP_RTC_INTERRUPTS_REG,
>  			val | OMAP_RTC_INTERRUPTS_IT_ALARM2);
> +
> +	/*
> +	 * first check if ALARM2 has fired, if not then check if
> +	 * our calculations started right before the rollover, try again
> +	 * in case of rollover
> +	 */
> +	if (!(OMAP_RTC_STATUS_ALARM2 && rtc_read(omap_rtc_power_off_rtc,
> +						 OMAP_RTC_STATUS_REG)) &&
> +	    seconds != rtc_read(omap_rtc_power_off_rtc, OMAP_RTC_SECONDS_REG))
> +		goto again;
> +

Can you use a while loop instead of goto?

>  	rtc->type->lock(rtc);
>  
>  	/*
> -	 * Wait for alarm to trigger (within two seconds) and external PMIC to
> +	 * Wait for alarm to trigger (within one second) and external PMIC to
>  	 * power off the system. Add a 500 ms margin for external latencies
>  	 * (e.g. debounce circuits).
>  	 */
> -	mdelay(2500);
> +	mdelay(1500);
>  }
>  
>  static const struct rtc_class_ops omap_rtc_ops = {
> -- 
> 1.9.1
>
Johan Hovold Aug. 14, 2018, 9:23 a.m. UTC | #2
On Wed, Jul 25, 2018 at 11:21:22AM +0530, Keerthy wrote:
> Cut down the shutdown time from 2 seconds to 1 sec. In case of roll
> over try again.
> 
> Signed-off-by: Keerthy <j-keerthy@ti.com>
> ---
> 
> Changes in v5:
> 
>   * Added an additional check to see if ALARM2 status is not set
>     before retrying.
>   * Cleaned up comments
>   * Also reduced mdelay to 1S lesser as per this commit
> 
>  drivers/rtc/rtc-omap.c | 28 ++++++++++++++++++----------
>  1 file changed, 18 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
> index 44ff4cc..caa6da6 100644
> --- a/drivers/rtc/rtc-omap.c
> +++ b/drivers/rtc/rtc-omap.c
> @@ -421,12 +421,6 @@ static int omap_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
>   * The RTC can be used to control an external PMIC via the pmic_power_en pin,
>   * which can be configured to transition to OFF on ALARM2 events.
>   *
> - * Notes:
> - * The two-second alarm offset is the shortest offset possible as the alarm
> - * registers must be set before the next timer update and the offset
> - * calculation is too heavy for everything to be done within a single access
> - * period (~15 us).
> - *
>   * Called with local interrupts disabled.
>   */
>  static void omap_rtc_power_off(void)
> @@ -435,17 +429,20 @@ static void omap_rtc_power_off(void)
>  	struct rtc_time tm;
>  	unsigned long now;
>  	u32 val;
> +	int seconds;

Nit: I'd place this above val to maintain the reverse xmas-tree style.

>  
>  	rtc->type->unlock(rtc);
>  	/* enable pmic_power_en control */
>  	val = rtc_readl(rtc, OMAP_RTC_PMIC_REG);
>  	rtc_writel(rtc, OMAP_RTC_PMIC_REG, val | OMAP_RTC_PMIC_POWER_EN_EN);
>  
> -	/* set alarm two seconds from now */
> +again:
> +	/* set alarm one second from now */
>  	omap_rtc_read_time_raw(rtc, &tm);
> +	seconds = tm.tm_sec;
>  	bcd2tm(&tm);
>  	rtc_tm_to_time(&tm, &now);
> -	rtc_time_to_tm(now + 2, &tm);
> +	rtc_time_to_tm(now + 1, &tm);
>  
>  	if (tm2bcd(&tm) < 0) {
>  		dev_err(&rtc->rtc->dev, "power off failed\n");
> @@ -470,14 +467,25 @@ static void omap_rtc_power_off(void)
>  	val = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
>  	rtc_writel(rtc, OMAP_RTC_INTERRUPTS_REG,
>  			val | OMAP_RTC_INTERRUPTS_IT_ALARM2);
> +
> +	/*
> +	 * first check if ALARM2 has fired, if not then check if
> +	 * our calculations started right before the rollover, try again
> +	 * in case of rollover
> +	 */

This is unnecessarily verbose; I'd rephrase it as something like:

	/* Retry in case roll over happened before alarm was armed. */

> +	if (!(OMAP_RTC_STATUS_ALARM2 && rtc_read(omap_rtc_power_off_rtc,
> +						 OMAP_RTC_STATUS_REG)) &&
> +	    seconds != rtc_read(omap_rtc_power_off_rtc, OMAP_RTC_SECONDS_REG))
> +		goto again;

And this is clearly broken. First, you use boolean && instead of the &
bit operation.

Second, you need to check the status register *after* checking for
roll-over, as I already mentioned.

Also, use the rtc pointer rather than omap_rtc_power_off_rtc, which will
allow for more readable code.

I also strongly suggest you split the conditional, and use val to store
the status register value, that is:

	if (rtc_read(rtc, OMAP_RTC_SECONDS_REG) != seconds) {
		val = rtc_read(rtc, OMAP_RTC_STATUS_REG);
		if (!(val & OMAP_RTC_STATUS_ALARM2))
			goto again;
	}

> +
>  	rtc->type->lock(rtc);
>  
>  	/*
> -	 * Wait for alarm to trigger (within two seconds) and external PMIC to
> +	 * Wait for alarm to trigger (within one second) and external PMIC to
>  	 * power off the system. Add a 500 ms margin for external latencies
>  	 * (e.g. debounce circuits).
>  	 */
> -	mdelay(2500);
> +	mdelay(1500);
>  }
>  
>  static const struct rtc_class_ops omap_rtc_ops = {

Johan
Johan Hovold Aug. 14, 2018, 9:27 a.m. UTC | #3
On Wed, Jul 25, 2018 at 11:30:18AM +0200, Alexandre Belloni wrote:
> Hi,
> 
> On 25/07/2018 11:21:22+0530, Keerthy wrote:
> > Cut down the shutdown time from 2 seconds to 1 sec. In case of roll
> > over try again.
> > 
> > Signed-off-by: Keerthy <j-keerthy@ti.com>

> >  static void omap_rtc_power_off(void)
> > @@ -435,17 +429,20 @@ static void omap_rtc_power_off(void)
> >  	struct rtc_time tm;
> >  	unsigned long now;
> >  	u32 val;
> > +	int seconds;
> >  
> >  	rtc->type->unlock(rtc);
> >  	/* enable pmic_power_en control */
> >  	val = rtc_readl(rtc, OMAP_RTC_PMIC_REG);
> >  	rtc_writel(rtc, OMAP_RTC_PMIC_REG, val | OMAP_RTC_PMIC_POWER_EN_EN);
> >  
> > -	/* set alarm two seconds from now */
> > +again:
> > +	/* set alarm one second from now */
> >  	omap_rtc_read_time_raw(rtc, &tm);
> > +	seconds = tm.tm_sec;
> >  	bcd2tm(&tm);
> >  	rtc_tm_to_time(&tm, &now);
> > -	rtc_time_to_tm(now + 2, &tm);
> > +	rtc_time_to_tm(now + 1, &tm);
> >  
> >  	if (tm2bcd(&tm) < 0) {
> >  		dev_err(&rtc->rtc->dev, "power off failed\n");
> > @@ -470,14 +467,25 @@ static void omap_rtc_power_off(void)
> >  	val = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
> >  	rtc_writel(rtc, OMAP_RTC_INTERRUPTS_REG,
> >  			val | OMAP_RTC_INTERRUPTS_IT_ALARM2);
> > +
> > +	/*
> > +	 * first check if ALARM2 has fired, if not then check if
> > +	 * our calculations started right before the rollover, try again
> > +	 * in case of rollover
> > +	 */
> > +	if (!(OMAP_RTC_STATUS_ALARM2 && rtc_read(omap_rtc_power_off_rtc,
> > +						 OMAP_RTC_STATUS_REG)) &&
> > +	    seconds != rtc_read(omap_rtc_power_off_rtc, OMAP_RTC_SECONDS_REG))
> > +		goto again;
> > +
> 
> Can you use a while loop instead of goto?

I think a goto is warranted here as it allows for more readable code
with less indentation. And the exception case it is used for is truly an
exception that a single retry would take care of.

Johan
J, KEERTHY Aug. 14, 2018, 9:32 a.m. UTC | #4
On Wednesday 25 July 2018 03:00 PM, Alexandre Belloni wrote:
> Hi,
> 
> On 25/07/2018 11:21:22+0530, Keerthy wrote:
>> Cut down the shutdown time from 2 seconds to 1 sec. In case of roll
>> over try again.
>>
>> Signed-off-by: Keerthy <j-keerthy@ti.com>
>> ---
>>
>> Changes in v5:
>>
>>   * Added an additional check to see if ALARM2 status is not set
>>     before retrying.
>>   * Cleaned up comments
>>   * Also reduced mdelay to 1S lesser as per this commit
>>
>>  drivers/rtc/rtc-omap.c | 28 ++++++++++++++++++----------
>>  1 file changed, 18 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
>> index 44ff4cc..caa6da6 100644
>> --- a/drivers/rtc/rtc-omap.c
>> +++ b/drivers/rtc/rtc-omap.c
>> @@ -421,12 +421,6 @@ static int omap_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
>>   * The RTC can be used to control an external PMIC via the pmic_power_en pin,
>>   * which can be configured to transition to OFF on ALARM2 events.
>>   *
>> - * Notes:
>> - * The two-second alarm offset is the shortest offset possible as the alarm
>> - * registers must be set before the next timer update and the offset
>> - * calculation is too heavy for everything to be done within a single access
>> - * period (~15 us).
>> - *
>>   * Called with local interrupts disabled.
>>   */
>>  static void omap_rtc_power_off(void)
>> @@ -435,17 +429,20 @@ static void omap_rtc_power_off(void)
>>  	struct rtc_time tm;
>>  	unsigned long now;
>>  	u32 val;
>> +	int seconds;
>>  
>>  	rtc->type->unlock(rtc);
>>  	/* enable pmic_power_en control */
>>  	val = rtc_readl(rtc, OMAP_RTC_PMIC_REG);
>>  	rtc_writel(rtc, OMAP_RTC_PMIC_REG, val | OMAP_RTC_PMIC_POWER_EN_EN);
>>  
>> -	/* set alarm two seconds from now */
>> +again:
>> +	/* set alarm one second from now */
>>  	omap_rtc_read_time_raw(rtc, &tm);
>> +	seconds = tm.tm_sec;
>>  	bcd2tm(&tm);
>>  	rtc_tm_to_time(&tm, &now);
>> -	rtc_time_to_tm(now + 2, &tm);
>> +	rtc_time_to_tm(now + 1, &tm);
>>  
>>  	if (tm2bcd(&tm) < 0) {
>>  		dev_err(&rtc->rtc->dev, "power off failed\n");
>> @@ -470,14 +467,25 @@ static void omap_rtc_power_off(void)
>>  	val = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
>>  	rtc_writel(rtc, OMAP_RTC_INTERRUPTS_REG,
>>  			val | OMAP_RTC_INTERRUPTS_IT_ALARM2);
>> +
>> +	/*
>> +	 * first check if ALARM2 has fired, if not then check if
>> +	 * our calculations started right before the rollover, try again
>> +	 * in case of rollover
>> +	 */
>> +	if (!(OMAP_RTC_STATUS_ALARM2 && rtc_read(omap_rtc_power_off_rtc,
>> +						 OMAP_RTC_STATUS_REG)) &&
>> +	    seconds != rtc_read(omap_rtc_power_off_rtc, OMAP_RTC_SECONDS_REG))
>> +		goto again;
>> +
> 
> Can you use a while loop instead of goto?

Apologies for the late reply. A one time retry should be able to take
care of the exception case.

> 
>>  	rtc->type->lock(rtc);
>>  
>>  	/*
>> -	 * Wait for alarm to trigger (within two seconds) and external PMIC to
>> +	 * Wait for alarm to trigger (within one second) and external PMIC to
>>  	 * power off the system. Add a 500 ms margin for external latencies
>>  	 * (e.g. debounce circuits).
>>  	 */
>> -	mdelay(2500);
>> +	mdelay(1500);
>>  }
>>  
>>  static const struct rtc_class_ops omap_rtc_ops = {
>> -- 
>> 1.9.1
>>
>
J, KEERTHY Aug. 14, 2018, 9:54 a.m. UTC | #5
On Tuesday 14 August 2018 02:53 PM, Johan Hovold wrote:
> On Wed, Jul 25, 2018 at 11:21:22AM +0530, Keerthy wrote:
>> Cut down the shutdown time from 2 seconds to 1 sec. In case of roll
>> over try again.
>>
>> Signed-off-by: Keerthy <j-keerthy@ti.com>
>> ---
>>
>> Changes in v5:
>>
>>   * Added an additional check to see if ALARM2 status is not set
>>     before retrying.
>>   * Cleaned up comments
>>   * Also reduced mdelay to 1S lesser as per this commit
>>
>>  drivers/rtc/rtc-omap.c | 28 ++++++++++++++++++----------
>>  1 file changed, 18 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
>> index 44ff4cc..caa6da6 100644
>> --- a/drivers/rtc/rtc-omap.c
>> +++ b/drivers/rtc/rtc-omap.c
>> @@ -421,12 +421,6 @@ static int omap_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
>>   * The RTC can be used to control an external PMIC via the pmic_power_en pin,
>>   * which can be configured to transition to OFF on ALARM2 events.
>>   *
>> - * Notes:
>> - * The two-second alarm offset is the shortest offset possible as the alarm
>> - * registers must be set before the next timer update and the offset
>> - * calculation is too heavy for everything to be done within a single access
>> - * period (~15 us).
>> - *
>>   * Called with local interrupts disabled.
>>   */
>>  static void omap_rtc_power_off(void)
>> @@ -435,17 +429,20 @@ static void omap_rtc_power_off(void)
>>  	struct rtc_time tm;
>>  	unsigned long now;
>>  	u32 val;
>> +	int seconds;
> 
> Nit: I'd place this above val to maintain the reverse xmas-tree style.

okay

> 
>>  
>>  	rtc->type->unlock(rtc);
>>  	/* enable pmic_power_en control */
>>  	val = rtc_readl(rtc, OMAP_RTC_PMIC_REG);
>>  	rtc_writel(rtc, OMAP_RTC_PMIC_REG, val | OMAP_RTC_PMIC_POWER_EN_EN);
>>  
>> -	/* set alarm two seconds from now */
>> +again:
>> +	/* set alarm one second from now */
>>  	omap_rtc_read_time_raw(rtc, &tm);
>> +	seconds = tm.tm_sec;
>>  	bcd2tm(&tm);
>>  	rtc_tm_to_time(&tm, &now);
>> -	rtc_time_to_tm(now + 2, &tm);
>> +	rtc_time_to_tm(now + 1, &tm);
>>  
>>  	if (tm2bcd(&tm) < 0) {
>>  		dev_err(&rtc->rtc->dev, "power off failed\n");
>> @@ -470,14 +467,25 @@ static void omap_rtc_power_off(void)
>>  	val = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
>>  	rtc_writel(rtc, OMAP_RTC_INTERRUPTS_REG,
>>  			val | OMAP_RTC_INTERRUPTS_IT_ALARM2);
>> +
>> +	/*
>> +	 * first check if ALARM2 has fired, if not then check if
>> +	 * our calculations started right before the rollover, try again
>> +	 * in case of rollover
>> +	 */
> 
> This is unnecessarily verbose; I'd rephrase it as something like:
> 
> 	/* Retry in case roll over happened before alarm was armed. */

Okay

> 
>> +	if (!(OMAP_RTC_STATUS_ALARM2 && rtc_read(omap_rtc_power_off_rtc,
>> +						 OMAP_RTC_STATUS_REG)) &&
>> +	    seconds != rtc_read(omap_rtc_power_off_rtc, OMAP_RTC_SECONDS_REG))
>> +		goto again;
> 
> And this is clearly broken. First, you use boolean && instead of the &
> bit operation.

Ah my bad. I will fix it.

> 
> Second, you need to check the status register *after* checking for
> roll-over, as I already mentioned.
> 
> Also, use the rtc pointer rather than omap_rtc_power_off_rtc, which will
> allow for more readable code.

Okay

> 
> I also strongly suggest you split the conditional, and use val to store
> the status register value, that is:
> 
> 	if (rtc_read(rtc, OMAP_RTC_SECONDS_REG) != seconds) {
> 		val = rtc_read(rtc, OMAP_RTC_STATUS_REG);
> 		if (!(val & OMAP_RTC_STATUS_ALARM2))
> 			goto again;
> 	}
> 
>> +
>>  	rtc->type->lock(rtc);
>>  
>>  	/*
>> -	 * Wait for alarm to trigger (within two seconds) and external PMIC to
>> +	 * Wait for alarm to trigger (within one second) and external PMIC to
>>  	 * power off the system. Add a 500 ms margin for external latencies
>>  	 * (e.g. debounce circuits).
>>  	 */
>> -	mdelay(2500);
>> +	mdelay(1500);
>>  }
>>  
>>  static const struct rtc_class_ops omap_rtc_ops = {
> 
> Johan
>
diff mbox series

Patch

diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
index 44ff4cc..caa6da6 100644
--- a/drivers/rtc/rtc-omap.c
+++ b/drivers/rtc/rtc-omap.c
@@ -421,12 +421,6 @@  static int omap_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
  * The RTC can be used to control an external PMIC via the pmic_power_en pin,
  * which can be configured to transition to OFF on ALARM2 events.
  *
- * Notes:
- * The two-second alarm offset is the shortest offset possible as the alarm
- * registers must be set before the next timer update and the offset
- * calculation is too heavy for everything to be done within a single access
- * period (~15 us).
- *
  * Called with local interrupts disabled.
  */
 static void omap_rtc_power_off(void)
@@ -435,17 +429,20 @@  static void omap_rtc_power_off(void)
 	struct rtc_time tm;
 	unsigned long now;
 	u32 val;
+	int seconds;
 
 	rtc->type->unlock(rtc);
 	/* enable pmic_power_en control */
 	val = rtc_readl(rtc, OMAP_RTC_PMIC_REG);
 	rtc_writel(rtc, OMAP_RTC_PMIC_REG, val | OMAP_RTC_PMIC_POWER_EN_EN);
 
-	/* set alarm two seconds from now */
+again:
+	/* set alarm one second from now */
 	omap_rtc_read_time_raw(rtc, &tm);
+	seconds = tm.tm_sec;
 	bcd2tm(&tm);
 	rtc_tm_to_time(&tm, &now);
-	rtc_time_to_tm(now + 2, &tm);
+	rtc_time_to_tm(now + 1, &tm);
 
 	if (tm2bcd(&tm) < 0) {
 		dev_err(&rtc->rtc->dev, "power off failed\n");
@@ -470,14 +467,25 @@  static void omap_rtc_power_off(void)
 	val = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
 	rtc_writel(rtc, OMAP_RTC_INTERRUPTS_REG,
 			val | OMAP_RTC_INTERRUPTS_IT_ALARM2);
+
+	/*
+	 * first check if ALARM2 has fired, if not then check if
+	 * our calculations started right before the rollover, try again
+	 * in case of rollover
+	 */
+	if (!(OMAP_RTC_STATUS_ALARM2 && rtc_read(omap_rtc_power_off_rtc,
+						 OMAP_RTC_STATUS_REG)) &&
+	    seconds != rtc_read(omap_rtc_power_off_rtc, OMAP_RTC_SECONDS_REG))
+		goto again;
+
 	rtc->type->lock(rtc);
 
 	/*
-	 * Wait for alarm to trigger (within two seconds) and external PMIC to
+	 * Wait for alarm to trigger (within one second) and external PMIC to
 	 * power off the system. Add a 500 ms margin for external latencies
 	 * (e.g. debounce circuits).
 	 */
-	mdelay(2500);
+	mdelay(1500);
 }
 
 static const struct rtc_class_ops omap_rtc_ops = {