mbed LPC17xx USB device not working

[vvkaggarwal12]

Description of defect

I am working on mbed LPC1768 board.
I build the code for USBSerial Example code for this board.
After flashing the code i am getting below error on UART Serial:

Error␣Status:␣0x80FF0144␣Code:␣324␣Module:␣255
Error␣Message:␣Assertion␣failed:␣status␣==␣osOK
Location:␣0x4295
File:␣.\mbed-os\rtos\source\ThisThread.cpp+225
Error␣Value:␣0x0
Current␣Thread:␣main␣Id:␣0x100014B4␣Entry:␣0x5679␣StackSize:␣0x1000␣StackMem:␣0x10001D98␣SP:␣0x10002CC4␣

And USB is not enumerating on the host side.
After investigating, in file targets/TARGET_NXP/USBHAL_LPC17xx.cpp, line 414, ThisThread::sleep_for is causing this issue.
When i replaced that line of code with wait_us it works.

Target(s) affected by this defect ?

NXP LPC17xx

Toolchain(s) (name and version) displaying this defect ?

arm gcc v9

What version of Mbed-os are you using (tag or sha) ?

mbed-os-6.1.0 - a6207ca

What version(s) of tools are you using. List all that apply (E.g. mbed-cli)

build using command line python 3.7.5

How is this defect reproduced ?

Build the code for any USB device example and flash the bin file to LPC17xx target.

[ciarmcom]

Thank you for raising this detailed GitHub issue. I am now notifying our internal issue triagers.
Internal Jira reference: https://jira.arm.com/browse/MBOTRIAGE-2745

[0xc0170]

After investigating, in file targets/TARGET_NXP/USBHAL_LPC17xx.cpp, line 414, ThisThread::sleep_for is causing this issue.
When i replaced that line of code with wait_us it works.

    osStatus_t status = osDelay(rel_time.count());
    MBED_ASSERT(status == osOK);

Can you check why this assert is failing ? I believe it is because the sleep_for() is executed from ISR, so an error is returned. or IS is masked (most probably). This is the function executing USBPhyHw::init(USBPhyEvents *events). I only see there NVIC_DisableIRQ(USB_IRQn);. Please check what is being returned and if ISR are really disabled.

[vvkaggarwal12]

After investigating, in file targets/TARGET_NXP/USBHAL_LPC17xx.cpp, line 414, ThisThread::sleep_for is causing this issue.
When i replaced that line of code with wait_us it works.

    osStatus_t status = osDelay(rel_time.count());
    MBED_ASSERT(status == osOK);

Can you check why this assert is failing ? I believe it is because the sleep_for() is executed from ISR, so an error is returned. or IS is masked (most probably). This is the function executing USBPhyHw::init(USBPhyEvents *events). I only see there NVIC_DisableIRQ(USB_IRQn);. Please check what is being returned and if ISR are really disabled.

As you said, it is being called from ISR. That is the reason for this error. But why this init function is being called from ISR. Please check https://github.com/ARMmbed/mbed-os/blob/master/targets/TARGET_NXP/USBHAL_LPC17.cpp line number 414.

[0xc0170]

Yes, but dont know the app flow thus would check the callstack. The best would be to step into sleep_for -> osDelay and find out why it returns an error - is it because interrupts are masked or any active interrupt ? Run a debug session to find out.

[vvkaggarwal12]

Yes, but dont know the app flow thus would check the callstack. The best would be to step into sleep_for -> osDelay and find out why it returns error - is it because interrupts are masked or any active interrupt ? Run a debug session to find out.

It is because the interrupts are masked. Don't have idea from where the interrupts are getting masked during this process.

[vvkaggarwal12]

Yes, but dont know the app flow thus would check the callstack. The best would be to step into sleep_for -> osDelay and find out why it returns error - is it because interrupts are masked or any active interrupt ? Run a debug session to find out.

I think before initializing the phy in USBSerial.cpp, USBDevice::init() calls lock() function which is disabling all interrupts.

[0xc0170]

void USBDevice::init()
{
    lock();

    if (!_initialized) {
        this->_phy->init(this);
        _max_packet_size_ep0 = this->_phy->ep0_set_max_packet(MAX_PACKET_SIZE_EP0);
        _initialized = true;
    }

    unlock();
}

correct, just found it. sleep_for() should not be there as it is not suitable. As this is very short timeout, can you send a pull request using wait_us instead? that fixes it as you stated earlier. Thanks

[vvkaggarwal12]

void USBDevice::init()
{
    lock();

    if (!_initialized) {
        this->_phy->init(this);
        _max_packet_size_ep0 = this->_phy->ep0_set_max_packet(MAX_PACKET_SIZE_EP0);
        _initialized = true;
    }

    unlock();
}

correct, just found it. sleep_for() should not be there as it is not suitable. As this is very short timeout, can you send a pull request using wait_us instead? that fixes it as you stated earlier. Thanks

Thank you very much for the help.
Yes sure i will give a pull request for this.