Issue with RTC on imx8mm

ashikp6 · ‎04-19-2023

Hi,
I am using custom board based on imx8mm with android 11.

When i use the Google desk clock application i dont see the RTC apis from drivers being called. Also the board doesnt come back from deep sleep(suspend) when the alarm triggered, even though the alarm is expected to bring the board to wakeup.
(Same application i have tried on my mobile phone and i am able to see the board coming out from suspend and showing the alarm notification)

We are using only the internal RTC.
DTS used is,
snvs_rtc

snvs_rtc: snvs-rtc-lp {
                    compatible = "fsl,sec-v4.0-mon-rtc-lp";
                    regmap = <&snvs>;
                    offset = <0x34>;
                    interrupts = <GIC_SPI 19 IRQ_TYPE_LEVEL_HIGH>,
                             <GIC_SPI 20 IRQ_TYPE_LEVEL_HIGH>;
                    clocks = <&clk IMX8MM_CLK_SNVS_ROOT>;
                    clock-names = "snvs-rtc";
                };

Also tried using the following commands,
echo +15 > /sys/class/rtc/rtc0/wakealarm
echo mem > /sys/power/state
In this scenario board goes to suspend and wakes up after 15s and i am seeing the RTC driver prints.

Why is the application not able to use rtc driver and trigger the interrupt to wake up the board ?
Thanks,
Ashik

ashikp6 · ‎04-24-2023

Hi @Dhruvit ,
Thanks for the suggestion.

Linked RTC with system clock using hwclock command.

When i try the below command to set alarm

echo +15 > /sys/class/rtc/rtc0/wakealarm

I can see the alarm being set,

nitrogen8mm:/ # cat /proc/driver/rtc                                                                                                                                                                         
rtc_time	: 11:10:25
rtc_date	: 2023-04-20
alrm_time	: 11:10:36
alrm_date	: 2023-04-20
alarm_IRQ	: yes
alrm_pending	: no
update IRQ enabled	: no
periodic IRQ enabled	: no
periodic IRQ frequency	: 1
max user IRQ frequency	: 64
24hr		: yes

but when i set from the alarm application, alarm IRQ is always 'no' and the alarm time doesnt change

Dhruvit · ‎04-25-2023

Hi @ashikp6,

I hope you are doing well.

It seems the Application is not using the correct RTC or does not have access to it.

Is there any other RTC available on the system?

# ls -la /dev/rtc*

One can refer to the below-mentioned links for more information.

https://stackoverflow.com/questions/14398127/rtc-wakeup-is-not-working

https://stackoverflow.com/questions/23821356/android-sys-rtc-wakealarm-does-not-boot-device-when-off

Please try adding the below the line in ueventd.nxp.rc

/dev/rtc0 0666 system system

Thanks & Regards,
Dhruvit Vasavada

ashikp6 · ‎05-04-2023

Hi @Dhruvit

I tried the same application in my phone with android 11. There the application seems to be working as expected and brings the board from suspend mode when the alarm rings.

i am using only one rtc.Output of the above command is
/dev/rtc0

Dhruvit · ‎05-04-2023

Hi @ashikp6,

I hope you are doing well.

This issue could be due to the app not having permission to use RTC.

Have you tried adding the below line in ueventd.rc

/dev/rtc0 0666 system system

Thanks & Regards,
Dhruvit Vasavada.

ashikp6 · ‎05-09-2023

Hi @Dhruvit ,

Tried adding

/dev/rtc0 0666 system system to /system/etc/ueventd.rc file. (Attached the updated file)

Set alarm from application( google desk clock).Still not seeing the alarm interrupt being set as shown below
rtc_time : 11:40:56
rtc_date : 2023-05-09
alrm_time : 00:00:00
alrm_date : 1970-01-01
alarm_IRQ : no
alrm_pending : no
updateIRQ enabled : no
periodic IRQ enabled : no
periodic IRQ frequency : 1
max user IRQ frequency : 64 2
4hr : yes

Thanks,
Ashik