| From: Joakim Zhang <qiangqing.zhang@nxp.com> |
| Date: Thu, 31 Jan 2019 09:37:22 +0000 |
| Subject: can: flexcan: fix timeout when set small bitrate |
| |
| commit 247e5356a709eb49a0d95ff2a7f07dac05c8252c upstream. |
| |
| Current we can meet timeout issue when setting a small bitrate like |
| 10000 as follows on i.MX6UL EVK board (ipg clock = 66MHZ, per clock = |
| 30MHZ): |
| |
| | root@imx6ul7d:~# 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 |
| |
| 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 double to FLEXCAN_TIMEOUT_US to 100 can fix the issue. |
| |
| Meanwhile, Rasmus Villemoes reported that even with a timeout of 100, |
| flexcan_probe() fails on the MPC8309, which requires a value of at least |
| 140 to work reliably. 250 works for everyone. |
| |
| Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com> |
| Reviewed-by: Dong Aisheng <aisheng.dong@nxp.com> |
| Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de> |
| [bwh: Backported to 3.16: adjust context] |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| drivers/net/can/flexcan.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/drivers/net/can/flexcan.c |
| +++ b/drivers/net/can/flexcan.c |
| @@ -157,7 +157,7 @@ |
| |
| #define FLEXCAN_MB_CODE_MASK (0xf0ffffff) |
| |
| -#define FLEXCAN_TIMEOUT_US (50) |
| +#define FLEXCAN_TIMEOUT_US (250) |
| |
| /* |
| * FLEXCAN hardware feature flags |
