spi speed on up squared 6000 does not go over 1MHz

I want to communicate through spi from an up2 6000 and a microcontroller. On the up2 I am using ubuntu 20.04 with kernel 5.13 and the PREEMT_RT patch

Linux up 5.13.0-rt1 #1 SMP PREEMPT_RT Thu Oct 13 12:09:18 CEST 2022 x86_64 x86_64 x86_64 GNU/Linux

my program to communicate through spi sets the speed like this:

    int file_desctiptor = open("/dev/spidev1.0", O_RDWR);
    if (file_desctiptor < 0) {
        return -2;
    }

    // Set the spi mode
    if (ioctl(file_desctiptor, SPI_IOC_WR_MODE, (SPI_MODE_1 | SPI_CS_HIGH)) < 0) {
        close(file_desctiptor);
        return -3;
    }

    // Set the spi speed
    uint32_t speed{8000000};
    if (ioctl(file_desctiptor, SPI_IOC_WR_MAX_SPEED_HZ, &speed) < 0) {
        close(file_desctiptor);
        return -4;
    }

But on the logic analyzer the spi clock frequency never goes over 1MHz. However, when I change the speed value for less than 1MHz it actually works, so it must be a maximum set somewhere.

I also tried to read back the speed after setting it up like this:

    // Read the spi speed
    uint32_t actual_speed;
    if (ioctl(file_desctiptor, SPI_IOC_RD_MAX_SPEED_HZ, &actual_speed) < 0) {
        close(file_desctiptor);
        return -5;

And I was getting 8MHz but the clock on the logic analyzer was still 1MHz. I also got some logs of the linux kernel

The spidev driver is telling me the speed has been set correctly but the intel driver says the actual speed is 1MHz.

To enable spidev on the up2 6000 I use ACPI overloads. I also modified the max speed here:

/*
 * This ASL can be used to declare a spidev device on SPI1 CS0
 */
DefinitionBlock ("", "SSDT", 5, "INTEL", "SPIDEV0", 0x00000001)
{
    External (_SB.PC00.SPI1, DeviceObj)

    Scope (\_SB.PC00.SPI1)
    {
        Device (TP0)
        {
            Name (_HID, "SPT0001")  // _HID: Hardware ID
            Name (_DDN, "SPI test device connected to CS0")  // _DDN: DOS Device Name
            Name (_CRS, ResourceTemplate ()  // _CRS: Current Resource Settings
            {
                SpiSerialBusV2 (0x0000, PolarityLow, FourWireMode, 0x08,
                    ControllerInitiated, 8000000, ClockPolarityLow,
                    ClockPhaseFirst, "\\_SB.PC00.SPI1",
                    0x00, ResourceConsumer, , Exclusive,
                    )
            })
        }
    }
}

Any idea of what I am missing?