> From: Joakim Zhang > Sent: Thursday, January 31, 2019 4:49 PM [...] > > > Current we can meet timeout issue when setting a small bitrate like > > > 10000 as follows: > > > root@imx6qdlsolo:~# ip link set can0 up type can bitrate 10000 A > > > link change request failed with some changes committed already. > > > Interface can0 may have been left with an inconsistent > > > configuration, please check. > > > RTNETLINK answers: Connection timed out > > > > Which SoC are you using? Which clock rate has the flexcan IP core? > > We tested on i.MX6 series boards and all met this issue. And ipg clock rate is > 66MHZ, per clock rate is 30MHZ. > > > > It is caused by calling of flexcan_chip_unfreeze() timeout. > > > > > > Originally the code is using usleep_range(10, 20) for unfreeze > > > operation, but the patch (8badd65 can: flexcan: avoid calling > > > usleep_range from interrupt context) changed it into udelay(10) > > > which is only a half delay of before, there're also some other delay > changes. > > > > > > After only changed unfreeze delay back to udelay(20), the issue is gone. > > > So other timeout values are kept the same as 8badd65 changed. > > > > Can you change FLEXCAN_TIMEOUT_US instead? > > Of course, we can change FLEXCAN_TIMEOUT_US to 100, but this will > extend the time of enable/disable/softreset. > Which method do you think is better? > That seems not a big deal for an error case. So change FLEXCAN_TIMEOUT_US seems like a good suggestion to me. You can cook a patch with commit message updated. No need keep my author name as it's a different solution. Regards Dong Aisheng > Best Regards, > Joakim Zhang > > > > Signed-off-by: Dong Aisheng <aisheng.dong@xxxxxxx> > > > Signed-off-by: Joakim Zhang <qiangqing.zhang@xxxxxxx> > > > --- > > > drivers/net/can/flexcan.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c > > > index 2bca867bcfaa..1d3a9053bbeb 100644 > > > --- a/drivers/net/can/flexcan.c > > > +++ b/drivers/net/can/flexcan.c > > > @@ -530,7 +530,7 @@ static int flexcan_chip_unfreeze(struct > > > flexcan_priv > > *priv) > > > priv->write(reg, ®s->mcr); > > > > > > while (timeout-- && (priv->read(®s->mcr) & > FLEXCAN_MCR_FRZ_ACK)) > > > - udelay(10); > > > + udelay(20); > > > > > > if (priv->read(®s->mcr) & FLEXCAN_MCR_FRZ_ACK) > > > return -ETIMEDOUT; > > > > > > > Marc > > > > -- > > Pengutronix e.K. | Marc Kleine-Budde | > > Industrial Linux Solutions | Phone: +49-231-2826-924 | > > Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | > > Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
