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stm32: canio: Fix message cancellation

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.. it's necessary to wait for a cancellation request to actually free
the respective Tx mailbox
This commit is contained in:
Jeff Epler 2020-10-06 10:31:38 -05:00
parent abe0405d6e
commit eed3387f4e
1 changed files with 10 additions and 2 deletions
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12
ports/stm/common-hal/canio/CAN.c
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@ -241,13 +241,21 @@ void common_hal_canio_can_send(canio_can_obj_t *self, mp_obj_t message_in)
// //
// We don't strictly guarantee that we abort the oldest Tx request, // We don't strictly guarantee that we abort the oldest Tx request,
// rather we just abort a different index each time. This permits us // rather we just abort a different index each time. This permits us
// to avoid tracking this information altogether. // to just track a single cancel index
HAL_CAN_AbortTxRequest(&self->handle, 1 << (self->cancel_mailbox)); HAL_CAN_AbortTxRequest(&self->handle, 1 << (self->cancel_mailbox));
self->cancel_mailbox = (self->cancel_mailbox + 1) % 3; self->cancel_mailbox = (self->cancel_mailbox + 1) % 3;
// The abort request may not have completed immediately, so wait for
// the Tx mailbox to become free
do {
free_level = HAL_CAN_GetTxMailboxesFreeLevel(&self->handle);
} while (!free_level);
} }
HAL_StatusTypeDef status = HAL_CAN_AddTxMessage(&self->handle, &header, message->data, &mailbox); HAL_StatusTypeDef status = HAL_CAN_AddTxMessage(&self->handle, &header, message->data, &mailbox);
if (status != HAL_OK) { if (status != HAL_OK) {
mp_raise_OSError(MP_ENOMEM); // this is a "shouldn't happen" condition. we don't throw because the
// contract of send() is that it queues the packet to be sent if
// possible and does not signal success or failure to actually send.
return;
} }
// wait 8ms (hard coded for now) for TX to occur // wait 8ms (hard coded for now) for TX to occur