CAN message gets corrupt inside a FreeRTOS task

Kernel
31

I have tried to call SCB_CleanDCache_by_Addr but it doesn’t alter the situation.
This driver code is supplied by Atmel from Atmel Start.


/**
 * \brief Write a CAN message
 */
int32_t _can_async_write(struct _can_async_device *const dev, struct can_message *msg)
{
	struct _can_tx_fifo_entry *f = NULL;
	hri_mcan_txfqs_reg_t       put_index;

	if (hri_mcan_get_TXFQS_TFQF_bit(dev->hw)) {
		return ERR_NO_RESOURCE;
	}

	put_index = hri_mcan_read_TXFQS_TFQPI_bf(dev->hw);
	
PUT_INDEX = put_index;

#ifdef CONF_CAN0_ENABLED
	if (dev->hw == MCAN0) {
		f = (struct _can_tx_fifo_entry *)(can0_tx_fifo + put_index * CONF_CAN0_TBDS);
	}
#endif
#ifdef CONF_CAN1_ENABLED
	if (dev->hw == MCAN1) {
		f = (struct _can_tx_fifo_entry *)(can1_tx_fifo + put_index * CONF_CAN1_TBDS);
	}
#endif
	if (f == NULL) {
		return ERR_NO_RESOURCE;
	}

F = f;

	f->T0.bit.RTR = (msg->type == CAN_TYPE_REMOTE) ? 1 : 0;

	if (msg->fmt == CAN_FMT_EXTID) {
		f->T0.val     = msg->id;
		f->T0.bit.XTD = 1;
	} else {
		/* A standard identifier is stored into ID[28:18] */
		f->T0.val = msg->id << 18;
	}

	if (msg->len <= 8) {
		f->T1.bit.DLC = msg->len;
	} else if (msg->len <= 12) {
		f->T1.bit.DLC = 0x9;
	} else if (msg->len <= 16) {
		f->T1.bit.DLC = 0xA;
	} else if (msg->len <= 20) {
		f->T1.bit.DLC = 0xB;
	} else if (msg->len <= 24) {
		f->T1.bit.DLC = 0xC;
	} else if (msg->len <= 32) {
		f->T1.bit.DLC = 0xD;
	} else if (msg->len <= 48) {
		f->T1.bit.DLC = 0xE;
	} else if (msg->len <= 64) {
		f->T1.bit.DLC = 0xF;
	}

	f->T1.bit.FDF = hri_mcan_get_CCCR_FDOE_bit(dev->hw);
	f->T1.bit.BRS = hri_mcan_get_CCCR_BRSE_bit(dev->hw);

	memcpy(f->data, msg->data, msg->len);

SCB_CleanDCache_by_Addr ( (uint32_t*)f, sizeof(struct _can_tx_fifo_entry) );  // <<== Flushing the cache area that contains struct _can_tx_fifo_entry

	hri_mcan_write_TXBAR_reg(dev->hw, 1 << hri_mcan_read_TXFQS_TFQPI_bf(dev->hw));
	return ERR_NONE;
}

I have stepped a lot through the driver code… :slight_smile: and I can see struct _can_tx_fifo_entry being filled properly.

Could I been using the function SCB_CleanDCache_by_Addr in the wrong way?
f is address of struct _can_tx_fifo_entry.

If I disable the cache by calling SCB_DisableDCache() it gives the same result.

I think FreeRTOS does not enable the cache. true?
Being that the case if it is a Cache issue why does it work outside FreeRTOS and not inside?