Regression in IRQ_DIRECT_CONNECT behavior from NCS 1.7 to 1.9.1

[emh203]

I have an applications that was using NCS 1.7.1 in its west manifest.  I am going through the process of upgrading to 1.9.1

My application using zero latency IRQs and sets the config:

CONFIG_ZERO_LATENCY_IRQS=y

This work OK in in 1.7.1 but I get a static assertion failure in 1.9.1  

C:/ELI/machine_mailbox/nrf/lib/nrf_modem_lib/nrf_modem_os.c: In function 'read_task_create':
C:/ELI/machine_mailbox/zephyr/include/toolchain/gcc.h:61:36: error: static assertion failed: "Invalid interrupt priority. Values must not exceed IRQ_PRIO_LOWEST"
   61 | #define BUILD_ASSERT(EXPR, MSG...) _Static_assert(EXPR, "" MSG)
      |                                    ^~~~~~~~~~~~~~
C:/ELI/machine_mailbox/zephyr/include/arch/arm/aarch32/irq.h:97:2: note: in expansion of macro 'BUILD_ASSERT'
   97 |  BUILD_ASSERT((flags_p & IRQ_ZERO_LATENCY) || \
      |  ^~~~~~~~~~~~
C:/ELI/machine_mailbox/zephyr/include/arch/arm/aarch32/irq.h:127:2: note: in expansion of macro '_CHECK_PRIO'
  127 |  _CHECK_PRIO(priority_p, flags_p) \
      |  ^~~~~~~~~~~
C:/ELI/machine_mailbox/zephyr/include/irq.h:112:2: note: in expansion of macro 'ARCH_IRQ_DIRECT_CONNECT'
  112 |  ARCH_IRQ_DIRECT_CONNECT(irq_p, priority_p, isr_p, flags_p)
      |  ^~~~~~~~~~~~~~~~~~~~~~~
C:/ELI/machine_mailbox/nrf/lib/nrf_modem_lib/nrf_modem_os.c:334:2: note: in expansion of macro 'IRQ_DIRECT_CONNECT'
  334 |  IRQ_DIRECT_CONNECT(NRF_MODEM_APPLICATION_IRQ,
      |  ^~~~~~~~~~~~~~~~~~
[4/22] Building C object modules/nrf/lib/nrf_modem_lib/CMakeFiles/..__nrf__lib__nrf_modem_lib.dir/nrf_modem_lib.c.obj
ninja: build stopped: subcommand failed.

The issue is :

    IRQ_DIRECT_CONNECT(NRF_MODEM_APPLICATION_IRQ,

               NRF_MODEM_APPLICATION_IRQ_PRIORITY,

               rpc_proxy_irq_handler, UNUSED_FLAGS);

in nrf_modem_os.c

NRF_MODEM_APPLICATION_IRQ is set to a value of 6 in in both version.   Maybe this has something to do w/ Zephyr changing how it checks priorities at build time?

Setting NRF_MODEM_APPLICATION_IRQ to 5  pass the assertion check.    Can someone at Nordic take a look?

[Amanda Hsieh]

Hi, 

There are 8 (0-7) levels available in cortex-m. One level is dedicated to the kernel and one for ZLI. This leaves 6 levels (0-5) for application. They are translated to hardware levels 2-7. Because of that level 6 asserts. As for regression, it is more likely that previously this was not caught by static assert. There were no functional changes. So the recommendation is to use level 5. And it should be NRF_MODEM_APPLICATION_IRQ_PRIORITY that should be changed instead of NRF_MODEM_APPLICATION_IRQ. Here is the assert to catch this condition: https://github.com/zephyrproject-rtos/zephyr/pull/37505

Regards,
Amanda

[emh203]

Could we get someone @Nordic to fix this upstream?   NRF_MODEM_APPLICATION_IRQ_PRIORITY should be a value of 5 for NCS 1.9.1 to build without error.

[Amanda Hsieh]

Hi, 

Sorry for the delay. I can see the pull reflected in NCS1.9.1. Please try to run the following command and check again. 

cd ncs/nrf
git fetch --all
git pull
git checkout v1.9.1
west update 

-Amanda

[emh203]

It looks like the fix was actually in 2.0.0.

https://github.com/nrfconnect/sdk-nrf/blob/v1.9.1/lib/nrf_modem_lib/nrf_modem_os.c

Can this be backported to 1.9.1?   It looks like 2.0.0 has a lot of breaking changes across zephyr/NCS as it was a major upgrade.   

[Amanda Hsieh]

Hi, 

emh203 said:

https://github.com/nrfconnect/sdk-nrf/blob/v1.9.1/lib/nrf_modem_lib/nrf_modem_os.c

Can this be backported to 1.9.1? 

The link you provided is supported for v1.9.1. 

-Amanda

[emh203]

Sorry, I should have be more clear.

in nrf_modem_os.c  in 1.9.1:

this is what is used to set the proirity.

NRF_MODEM_APPLICATION_IRQ_PRIORITY

This is set in nrfxlib 1.9.1:

/nrfconnect/sdk-nrfxlib/blob/main/nrf_modem/include/nrf_modem_platform.h

and is hard coded to a value of 6 (which is the value I have to manually patch).

In nrf_modem_os.c  2.0.0

This symbol is defined:

#define APPLICATION_IRQ_PRIORITY IRQ_PRIO_LOWEST

which is used here:

IRQ_DIRECT_CONNECT(APPLICATION_IRQ, APPLICATION_IRQ_PRIORITY,
rpc_proxy_irq_handler, UNUSED_FLAGS);

on line 371.

This configuration builds correctly

 

What I trying to achieve is to simply add 1.9.1 to my manifest and have a clean build.     I don't think the change was ported into 1.9.1

Thanks,

Eli

[Amanda Hsieh]

Hi, 

Here is the PR: https://github.com/nrfconnect/sdk-nrf/pull/7774 for this case. It's merged into v2.0.0, and the developer said it can be backported to v1.9.1. 

-Amanda