RE: [PATCH] can: flexcan: fix timeout when set small bitrate

-----Original Message-----
From: Joakim Zhang
Sent: Thursday, January 31, 2019 5:37 PM
To: mkl@pengutronix.de; linux-can@vger.kernel.org
Cc: wg@grandegger.com; netdev@vger.kernel.org;
linux-kernel@vger.kernel.org; dl-linux-imx [off-list ref]; Joakim
Zhang [off-list ref]
Subject: [PATCH] can: flexcan: fix timeout when set small bitrate

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.

Signed-off-by: Joakim Zhang <redacted>

Reviewed-by: Dong Aisheng <aisheng.dong@nxp.com>

Regards
Dong Aisheng