Defining a thread with a K_FOREVER dealy will cause a compile error

[Ignacio]

According to Zephyr documentation it is possible to define a thread with K_FOREVER delay so it will not start till k_thread_start is called

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/0.3.0/zephyr/api/kernel_api.html?highlight=k_thread_start#_CPPv314k_thread_start7k_tid_t

However, if a thread is define with K_FOREVER will trigger the following compile issue:

K_THREAD_DEFINE(spis_tid, SPIS_STACK_SIZE, spis_thread, NULL, NULL, NULL,
		SPIS_PRIORITY, 0, K_FOREVER);

    incompatible types when initializing type 'int' using type 'k_timeout_t' {aka 'struct <anonymous>'}
    in expansion of macro 'Z_THREAD_INITIALIZER'
    in expansion of macro 'K_THREAD_DEFINE'
    In function 'spi_test_transceive':
    unused variable 'tx' [-Wunused-variable]
Build failed

[Håkon Alseth]

Hi,

 

You are viewing older documentation. The define itself takes in a int type, while the K_FOREVER is a type k_timeout_t.

Could you try providing "-1" as the delay? Similar to how its done here:

https://github.com/nrfconnect/sdk-zephyr/blob/v2.7.0-ncs1/samples/drivers/espi/src/espi_oob_handler.c#L28-L38

 

Kind regards,

Håkon

[Ignacio]

That works. Although latest Nordic documentation shows the same for k_thread_start

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/reference/kernel/threads/index.html?highlight=k_thread_start#c.k_thread_start

Zephyr latest version and 2.7.0 show the same info

https://docs.zephyrproject.org/2.7.0/reference/kernel/threads/index.html?highlight=k_thread_start#c.k_thread_start

Thus, it is my opinion that using K_FOREVER on the thread definition is the correct implementation. Setting value as "-1" should be a temporary workaround.