SPI driver doesn't activate the chip select pin on the Colibri iMX6 board

I am trying to use the spi-nor device driver to communicate with a SPI flash chip (N25q032a). I enabled the driver in the device tree and in the kernel.
When the driver is probing the device, I can see the correct pulses coming out from the SCLK and MOSI lines , but I don’t see any change in CS.

I can manually force the probing with

echo spi0.0 > /sys/bus/spi/drivers/spi-nor/bind

But the driver, as expected, cannot identify the chip:

spi-nor spi0.0: unrecognized JEDEC id bytes: ff ff ff ff ff ff
spi-nor: probe of spi0.0 failed with error -2
spi_imx 2008000.spi: probed

I tested the hardware by enabling the spidev module and using spidev_test to query the chip. The spidev driver activates the CS line, the chip responds and everything works fine. So I assume the hardware is OK.

Those are the lines I appended to the device tree, at the end of imx6ull-colibri-eval-v3.dts:

&mcp2515 {
	status = "disabled";

&spidev0 {
	status = "disabled";

&ecspi1 {
    spi_flash: n25q032a@0 {
        #address-cells = <1>;
        #size-cells = <1>;
        compatible = "jedec,spi-nor";
        reg = <0>;
        spi-max-frequency = <40000000>;
        status = "okay";

I don’t know what is happening. Am I missing something?

Thank you in advance,