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CAN: A minor improvement to can_txready design

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This commit is contained in:
Gregory Nutt 2015-11-15 06:36:30 -06:00
parent d6eb48d1ab
commit 815ec07b55
2 changed files with 20 additions and 11 deletions
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27
drivers/can.c
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@ -298,6 +298,7 @@ static void can_txready_work(FAR void *arg)
{ {
FAR struct can_dev_s *dev = (FAR struct can_dev_s *)arg; FAR struct can_dev_s *dev = (FAR struct can_dev_s *)arg;
irqstate_t flags; irqstate_t flags;
int ret;
canllvdbg("xmit head: %d queue: %d tail: %d\n", canllvdbg("xmit head: %d queue: %d tail: %d\n",
dev->cd_xmit.tx_head, dev->cd_xmit.tx_queue, dev->cd_xmit.tx_head, dev->cd_xmit.tx_queue,
@ -312,15 +313,23 @@ static void can_txready_work(FAR void *arg)
{ {
/* Send the next message in the FIFO. */ /* Send the next message in the FIFO. */
(void)can_xmit(dev); ret = can_xmit(dev);
/* Are there any threads waiting for space in the TX FIFO? */ /* If the message was successfully queued in the H/W FIFO, then
* can_txdone() should have been called. If the S/W FIFO were
* full before then there should now be free space in the S/W FIFO.
*/
if (dev->cd_ntxwaiters > 0) if (ret >= 0)
{ {
/* Yes.. Inform them that new xmit space is available */ /* Are there any threads waiting for space in the TX FIFO? */
(void)sem_post(&dev->cd_xmit.tx_sem); if (dev->cd_ntxwaiters > 0)
{
/* Yes.. Inform them that new xmit space is available */
(void)sem_post(&dev->cd_xmit.tx_sem);
}
} }
} }
@ -745,7 +754,7 @@ static ssize_t can_write(FAR struct file *filep, FAR const char *buffer,
if (inactive) if (inactive)
{ {
can_xmit(dev); (void)can_xmit(dev);
} }
/* Wait for a message to be sent */ /* Wait for a message to be sent */
@ -794,7 +803,7 @@ static ssize_t can_write(FAR struct file *filep, FAR const char *buffer,
if (inactive) if (inactive)
{ {
can_xmit(dev); (void)can_xmit(dev);
} }
/* Return the number of bytes that were sent */ /* Return the number of bytes that were sent */
@ -1242,8 +1251,8 @@ int can_txdone(FAR struct can_dev_s *dev)
* OK on success; a negated errno on failure. * OK on success; a negated errno on failure.
* *
* Assumptions: * Assumptions:
* Interrupts are disabled. This is required by can_xmit() which is called * Interrupts are disabled. This function may execute in the context of
* by this function. * and interrupt handler.
* *
****************************************************************************/ ****************************************************************************/

4
include/nuttx/can.h
View File

@ -646,8 +646,8 @@ int can_txdone(FAR struct can_dev_s *dev);
* OK on success; a negated errno on failure. * OK on success; a negated errno on failure.
* *
* Assumptions: * Assumptions:
* Interrupts are disabled. This is required by can_xmit() which is called * Interrupts are disabled. This function may execute in the context of
* by this function. * and interrupt handler.
* *
************************************************************************************/ ************************************************************************************/