flash_safe_execute returns -4 when both cores are in use

[sykacek]

I need to read data from the sensor and write the values into RP2040 internal flash. I thought that good approach would be use one core for handling the flash and the other for handling the sensor. I need to write data periodically (every 4 seconds), but flash_safe_execute returns -4 when executed. In the code below I use core 1 for writing to flash, although results are same when writing to flash from core 0 (I never use both cores for flash operations).

#include "pico/stdlib.h"
#include <stdio.h>

#include "pico/flash.h"
#include "pico/multicore.h"
#include "hardware/flash.h"
#include "hardware/sync.h"

#define LED		(25)

#define NVS_SIZE		(4096)
#define NVS_SECTORS		(446)
#define PAGE_SIZE		(256)
#define PAGE_SECTORS		(NVS_SECTORS * NVS_SIZE / PAGE_SIZE)

#define FLASH_WRITE_START	(0x42000)
#define FLASH_READ_START	(FLASH_WRITE_START + XIP_BASE)

#define FLASH_SECTORS		(256)

volatile int led = 1;
volatile uint32_t offset = FLASH_WRITE_START;
static unsigned char buffer[256] = "hello world from flash! 256";

void __not_in_flash_func(call_write_flash)(void *param){
	puts("call from write");
	(void)(param);

	flash_range_program(offset, buffer, 256);
	offset += 256;
}

void core1_entry(void) {
	/* when uncommented core 1 task crashes */
	//flash_safe_execute_core_init();

	while(1){	
		int val = multicore_fifo_pop_blocking();
		printf("value from core %d is %d\n", get_core_num(), val);
		
		if(val % 21 == 0){
			printf("writing to flash returned %d\n", flash_safe_execute(call_write_flash, NULL, 200));
		}
	}
}

bool core0_timer_callback(repeating_timer_t *rt){
	int i = *(int *)(rt->user_data);

	multicore_fifo_push_blocking(i++);
	printf("value from core %d is %d\n", get_core_num(), i);

	gpio_put(25, i % 2);
	*(int *)rt->user_data = i;
	/*if(i % 5 == 0){
		printf("writing to flash returned %d\n", flash_safe_execute(call_write_flash, NULL, 200));
	}*/

	return true;
}

int main(void){
	while(!stdio_init_all()){
		;
	}

/*
	uint32_t irqs = save_and_disable_interrupts();
	flash_range_erase(FLASH_WRITE_START, NVS_SECTORS * NVS_SIZE);
	restore_interrupts_from_disabled(irqs);

	sleep_ms(10000);
*/

	gpio_init(25);
	gpio_set_dir(25, GPIO_OUT);

	multicore_launch_core1(core1_entry);

	repeating_timer_t tim;
	add_repeating_timer_ms(200, core0_timer_callback, (void *)&led, &tim);

	while(1){
		tight_loop_contents();
	}
}

Commented section in main function does not seem to have any influence on results, flash_safe_execute returns -4 persists.
When first called flash_safe_execute_core_init() on core 1, I don't get any response from the core.
Assuming core0 is safe causes the whole system break after first flash call from core 1.

add_compile_definitions(PICO_FLASH_ASSUME_CORE0_SAFE=1)

Specifying binary type in CMakeLists.txt does not change anything

pico_set_binary_type(app copy_to_ram)

Just in case there is whole CMakeLists.txt below

cmake_minimum_required(VERSION 3.13)

include($ENV{PICO_SDK_PATH}/external/pico_sdk_import.cmake)

project(app)

pico_sdk_init()

add_compile_options(-Wall -Wextra)

add_executable(app
	main.c
)

target_include_directories(app PRIVATE
	${CMAKE_CURRENT_LIST_DIR}
)

target_link_libraries(app
	pico_stdlib
	hardware_flash
	pico_multicore
)

pico_enable_stdio_usb(app 1)
pico_enable_stdio_uart(app 1)
pico_add_extra_outputs(app)
pico_set_binary_type(app copy_to_ram)

add_custom_target(flash cp ${PROJECT_NAME}.uf2 /run/media/nero/RPI-RP2)

Why flash_safe_execute returns -4 and how to write to flash when both cores are running?

[kilograham]

You need to call

/**
 * \brief Initialize a core such that the other core can lock it out during \ref flash_safe_execute.
 * \ingroup pico_flash
 *
 * \note This is not necessary for FreeRTOS SMP, but should be used when launching via \ref multicore_launch_core1
 * \return true on success; there is no need to call \ref flash_safe_execute_core_deinit() on failure.
 */
bool flash_safe_execute_core_init(void);

On both cores if using multicore

[kilograham]

Note that multicore_fifo_push_blocking cannot currently be used if you are using multicore_lockout. See #2222 for RP2350 tho... you should probably just use a pico/util/queue.h in your code

[kilograham]

Also note, questons should be asked in the forums https://forums.raspberrypi.com/viewforum.php?f=143

[sykacek]

Thanks a lot!