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SAMV7 MCAN: When bitrate is changed, the MCAN has to be reset and there are lots of issues related to getting back to a healthy state if there is multithreaded access to the MCAN device. This commit handles a few of those issues, but there are more

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This commit is contained in:
Gregory Nutt 2015-08-18 11:56:07 -06:00
parent 4b96605f93
commit cfd4f943da
1 changed files with 20 additions and 2 deletions
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22
arch/arm/src/samv7/sam_mcan.c
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@ -2110,6 +2110,15 @@ static void mcan_reset(FAR struct can_dev_s *dev)
mcan_putreg(priv, SAM_MCAN_IE_OFFSET, 0);
mcan_putreg(priv, SAM_MCAN_TXBTIE_OFFSET, 0);
/* Make sure that all buffers are released.
*
* REVISIT: What if a thread is waiting for a buffer? The following
* will not wake up any waiting threads.
*/
sem_destroy(&priv->txfsem);
sem_init(&priv->txfsem, 0, config->ntxfifoq);
/* Disable peripheral clocking to the MCAN controller */
sam_disableperiph1(priv->config->pid);
@ -2403,6 +2412,12 @@ static int mcan_ioctl(FAR struct can_dev_s *dev, int cmd, unsigned long arg)
* is returned with the errno variable set to indicate the
* nature of the error.
* Dependencies: None
*
* REVISIT: There is probably a limitation here: If there are multiple
* threads trying to send CAN packets, when one of these threads reconfigures
* the bitrate, the MCAN hardware will be reset and the context of operation
* will be lost. Hence, this IOCTL can only safely be executed in quiescent
* time periods.
*/
case CANIOC_SET_BITTIMING:
@ -2415,7 +2430,7 @@ static int mcan_ioctl(FAR struct can_dev_s *dev, int cmd, unsigned long arg)
uint32_t tseg2;
uint32_t sjw;
uint32_t ie;
uint8_t state;
uint8_t state;
DEBUGASSERT(bt != NULL);
DEBUGASSERT(bt->bt_baud < SAMV7_MCANCLK_FREQUENCY);
@ -2461,11 +2476,14 @@ static int mcan_ioctl(FAR struct can_dev_s *dev, int cmd, unsigned long arg)
/* We we have successfully re-initialized, then restore the
* interrupt state.
*
* REVISIT: Since the hardware was reset, any pending TX
* activity was lost. Should we disable TX interrupts?
*/
if (ret == OK)
{
mcan_putreg(priv, SAM_MCAN_IE_OFFSET, ie);
mcan_putreg(priv, SAM_MCAN_IE_OFFSET, ie & ~priv->txints);
}
irqrestore(flags);