Changing device config in runtime

[robertkowalewski]

Hi,
I have a case where I need to update cs.delay (from SPI driver) value for wakeup frame sent to SPI slave device (for other messages cs.delay will have its default value which is 0). As device config is read-only structure, I cannot update that property in runtime. So I came up with an idea to allocate a "new" device structure and copy the origin device structure into it, and then changed a value of cs.delay. Does it have a chance to work? Is there other way to achieve the same goal?

Example:

struct device *tmp_dev = k_malloc(sizeof(struct device));

tmp_dev = k_malloc(sizeof(struct device));
memcpy(tmp_dev, dev, sizeof(struct device));

tmp_config = dev->config;
tmp_config->bus.config.cs.delay = 400;

spi_write_dt(&tmp_config->bus, &tx);

[yashi]

If you are not using the values from devicetree, you can just use plain i2c functions (without _dt suffix).
For spi_write_dt(), there is spi_write(), which takes dev, config, and tx_bufs. struct spi_config, or spi_cs_control within it, is what you need to check.

https://github.com/zephyrproject-rtos/zephyr/blob/main/include/zephyr/drivers/spi.h#L284-L315

You can pass your spi_config to your spi device how to operate.

[robertkowalewski]

Thanks for your answer, it was really helpful!