ChibiOS selection in OS

Feature request
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1

Would it be possible to add a ready template for ChibiOS, simillar how its done currently with FreeRTOS?

2

A software engineer from a ChibiOS related company contacted us a few weeks ago saying they have added ChibiOS support for LVGL.

I’ve followed up with him to see if they are interesting in sending a PR.

3

That would be great. Personally I’ve nearly done it, however for now the main problem is adapting the lvgl LTDC driver.

4

Oh, nice! What’s the problem with LTDC?

5

cc @liamHowatt

6

The main problem is that the driver relies heavily on the STM32 HAL which in ChibiOS is not present. Prior Ive done a project with uGFX and ChibiOS, there the driver was pretty universal hence it could run pretty much standalone.

7

I’ve successfully implemented ChibiOS, everything seems to work fine besides the using LTDC in double buffer mode which causes the timer_handler thread to get stopped on a semaphore that doesn’t seem to be lifted, however in single buffer mode it seems to work fine.

//Edit
I’ve indentified the code causing this. As soon as flush_wait_cb() from the LTDC drivers gets called which invoked my adaption of the lv_thread_sync_wait function it causes the semaphore to not be lifted. For other functions it does work correctly.

lv_result_t lv_thread_sync_wait(lv_thread_sync_t * pxCond)
{
    lv_result_t lvRes = LV_RESULT_OK;
    prvCheckCondInit(pxCond);
    
    chMtxLock(&pxCond->xSyncMutex);
    while(pxCond->xSyncSignal == FALSE) {
        pxCond->ulWaitingThreads++;
        chMtxUnlock(&pxCond->xSyncMutex);
        chSemWait(&pxCond->xCondWaitSemaphore);
        chMtxLock(&pxCond->xSyncMutex);
    }
    /* Reset the signal after waking up */
    pxCond->xSyncSignal = FALSE;
    chMtxUnlock(&pxCond->xSyncMutex);
    return lvRes;
}
8

Great news! Unfortunately I haven’t heard from my ChibiOS contact.

I don’t know ChibiOS but prvCheckCondInit(pxCond); seems to be initializing the condiation every time lv_thread_sync_wait is called. Shouldn’t it be done only once in lv_thread_sync_init?

9

Hello,

It has a check if its already initialized

static void prvCheckCondInit(lv_thread_sync_t *pxCond)
{
    if (!pxCond->is_initialized)
    {
        _enter_critical();
        prvCondInit(pxCond);
        _exit_critical();
    }
}