| Message ID | 1414579527-31100-4-git-send-email-b29396@freescale.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 10/29/2014 11:45 AM, Dong Aisheng wrote: > The spec mentions there may be a delay until the value written to > INIT can be read back due to the synchronization mechanism between the > two clock domains. But it does not indicate the exact clock cycles needed. > The 5us delay is a test value and seems ok. > > Without the delay, CCCR.CCE bit may fail to be set and then the > initialization fail sometimes when do repeatly up and down. > > Signed-off-by: Dong Aisheng <b29396@freescale.com> Applied to can/master. Thanks, Marc
diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c index e4ef146..6160b9c 100644 --- a/drivers/net/can/m_can/m_can.c +++ b/drivers/net/can/m_can/m_can.c @@ -296,6 +296,7 @@ static inline void m_can_config_endisable(const struct m_can_priv *priv, if (enable) { /* enable m_can configuration */ m_can_write(priv, M_CAN_CCCR, cccr | CCCR_INIT); + udelay(5); /* CCCR.CCE can only be set/reset while CCCR.INIT = '1' */ m_can_write(priv, M_CAN_CCCR, cccr | CCCR_INIT | CCCR_CCE); } else {
The spec mentions there may be a delay until the value written to INIT can be read back due to the synchronization mechanism between the two clock domains. But it does not indicate the exact clock cycles needed. The 5us delay is a test value and seems ok. Without the delay, CCCR.CCE bit may fail to be set and then the initialization fail sometimes when do repeatly up and down. Signed-off-by: Dong Aisheng <b29396@freescale.com> --- drivers/net/can/m_can/m_can.c | 1 + 1 file changed, 1 insertion(+)