queue-4.14/can-flexcan-fix-timeout-when-set-small-bitrate.patch

   1 From 247e5356a709eb49a0d95ff2a7f07dac05c8252c Mon Sep 17 00:00:00 2001
   2 From: Joakim Zhang <qiangqing.zhang@nxp.com>
   3 Date: Thu, 31 Jan 2019 09:37:22 +0000
   4 Subject: can: flexcan: fix timeout when set small bitrate
   5
   6 From: Joakim Zhang <qiangqing.zhang@nxp.com>
   7
   8 commit 247e5356a709eb49a0d95ff2a7f07dac05c8252c upstream.
   9
  10 Current we can meet timeout issue when setting a small bitrate like
  11 10000 as follows on i.MX6UL EVK board (ipg clock = 66MHZ, per clock =
  12 30MHZ):
  13
  14 | root@imx6ul7d:~# ip link set can0 up type can bitrate 10000
  15
  16 A link change request failed with some changes committed already.
  17 Interface can0 may have been left with an inconsistent configuration,
  18 please check.
  19
  20 | RTNETLINK answers: Connection timed out
  21
  22 It is caused by calling of flexcan_chip_unfreeze() timeout.
  23
  24 Originally the code is using usleep_range(10, 20) for unfreeze
  25 operation, but the patch (8badd65 can: flexcan: avoid calling
  26 usleep_range from interrupt context) changed it into udelay(10) which is
  27 only a half delay of before, there're also some other delay changes.
  28
  29 After double to FLEXCAN_TIMEOUT_US to 100 can fix the issue.
  30
  31 Meanwhile, Rasmus Villemoes reported that even with a timeout of 100,
  32 flexcan_probe() fails on the MPC8309, which requires a value of at least
  33 140 to work reliably. 250 works for everyone.
  34
  35 Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
  36 Reviewed-by: Dong Aisheng <aisheng.dong@nxp.com>
  37 Cc: linux-stable <stable@vger.kernel.org>
  38 Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
  39 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  40
  41 ---
  42  drivers/net/can/flexcan.c |    2 +-
  43  1 file changed, 1 insertion(+), 1 deletion(-)
  44
  45 --- a/drivers/net/can/flexcan.c
  46 +++ b/drivers/net/can/flexcan.c
  47 @@ -177,7 +177,7 @@
  48  #define FLEXCAN_MB_CNT_LENGTH(x)       (((x) & 0xf) << 16)
  49  #define FLEXCAN_MB_CNT_TIMESTAMP(x)    ((x) & 0xffff)
  50
  51 -#define FLEXCAN_TIMEOUT_US             (50)
  52 +#define FLEXCAN_TIMEOUT_US             (250)
  53
  54  /* FLEXCAN hardware feature flags
  55   *