Legato 21.05 and CONFIG_PREEMPT_RT

IoT Modules WP Series
22

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So, as I understood, WP7607 has hardware watchdog, and WP7702 has not. Right?
However, this command working on WP7702, and in the dmesg I see:

root@swi-mdm9x28-wp:~# dmesg | grep dog
[    0.077310] msm_watchdog b017000.qcom,wdt: wdog absent resource not present
[    0.077348] msm_watchdog b017000.qcom,wdt: msm_wdog_dt_to_pdata scandump sizes property not correct
[    0.077738] msm_watchdog b017000.qcom,wdt: Couldn't get memory for dump
[    0.077798] msm_watchdog b017000.qcom,wdt: MSM Watchdog Initialized

also in processes:

root@swi-mdm9x28-wp:~# ps aux | grep dog
root        16  0.0  0.0      0     0 ?        S    11:26   0:00 [msm_watchdog]
root      1219  0.1  0.7   3532  1404 ?        S<   11:26   0:00 watchdog

As I understand, msm_watchdog is hardware watchdog driver from Qualcomm.
Also, WP7702 kernel device tree includes mdm9607.dtsi file, and it has watchdog defined:

        qcom,wdt@b017000 {
                compatible = "qcom,msm-watchdog";
                reg = <0xb017000 0x1000>;
                reg-names = "wdt-base";
                interrupts = <0 3 0>, <0 4 0>;
                qcom,bark-time = <11000>;
                qcom,pet-time = <9360>;
                qcom,wakeup-enable;
        };

So, all points that hardware watchdog is present in WP7702. Outdated AT-command documentation?

23

Did you check ati8 to see whether it returns mcu version?

24

Here it is:

ati8
Legato Ver: 21.05.0_3f0c4092d807371cc51745399ded843f
Yocto Ver:  SWI9X06Y_03.00.13.00 2022-12-27_09:10:00
OS Ver: Linux version 4.14.253 (oe-user@oe-host) ( gcc version 9.3.0 (GCC), GNU ld (GNU Binutils) 2.34.0.20200220) #1 PREEMPT Tue Dec 27 08:09:00 UTC 2022
LK Ver: SWI9X06Y_03.00.13.00
RootFS Ver: SWI9X06Y_03.00.13.00 2022-12-27_09:10:00
UserFS Ver: unknown
MCU Ver: 002.015
25

i can see it has mcu

26

So, then the conclusion is WP7702 and WP7607 have hardware watchdog timer in the MCU application core, and I do not need to add external hardware watchdog time to the device design.

27

I checked again in AT command user guide, it says WP7702 cannot use this command, so I believe you need to use legato watchdog

28

The command is working on my WP7702 I got with devboard. I checked.
It’s all clear with Legato watchdog API, I already tested it.
My question was about external hardware watchdog IC, for the case when baseband or application MCU will hang.
If WP7607/7702 have internal hardware watchdog timer, then, of course, I do not need to put external watchdog IC on my board.

29

but the AT!MCUWATCHDOG cannot be used in WP7702 according to AT command user guide, I think it is not validated in WP7702
Of course you can double check with distributor and request this feature in WP7702

30

I’m just about internal hardware watchdog…
From my side, I can see that it present at 0xb017000 address, served by msm-watchdog driver, in WP7607 and in WP7702 as well. Then, when application MCU or broadband MCU will hang, they will be restarted by this watchdog automatically. Right?
My device will be installed on the top of pole, so, it will be not so easy to reach it.

31

problem here is I don’t know how you can verify this command: