target/linux/layerscape/patches-5.4/802-can-0026-can-flexcan-fix-deadlock-when-using-self-wakeup.patch

   1 From 59876225748221d7ebbdb9c892a2086420ddd80d Mon Sep 17 00:00:00 2001
   2 From: Sean Nyekjaer <sean@geanix.com>
   3 Date: Thu, 14 Nov 2019 19:56:28 +0800
   4 Subject: [PATCH] can: flexcan: fix deadlock when using self wakeup
   5
   6 When suspending, when there is still can traffic on the interfaces the
   7 flexcan immediately wakes the platform again. As it should :-). But it
   8 throws this error msg:
   9 [ 3169.378661] PM: noirq suspend of devices failed
  10
  11 On the way down to suspend the interface that throws the error message does
  12 call flexcan_suspend but fails to call flexcan_noirq_suspend. That means the
  13 flexcan_enter_stop_mode is called, but on the way out of suspend the driver
  14 only calls flexcan_resume and skips flexcan_noirq_resume, thus it doesn't call
  15 flexcan_exit_stop_mode. This leaves the flexcan in stop mode, and with the
  16 current driver it can't recover from this even with a soft reboot, it requires
  17 a hard reboot.
  18
  19 This patch can fix deadlock when using self wakeup, it happenes to be
  20 able to fix another issue that frames out-of-order in first IRQ handler
  21 run after wakeup.
  22
  23 In wakeup case, after system resume, frames received out-of-order,the
  24 problem is wakeup latency from frame reception to IRQ handler is much
  25 bigger than the counter overflow. This means it's impossible to sort the
  26 CAN frames by timestamp. The reason is that controller exits stop mode
  27 during noirq resume, then it can receive the frame immediately. If
  28 noirq reusme stage consumes much time, it will extend interrupt response
  29 time.
  30
  31 Fixes: de3578c198c6 ("can: flexcan: add self wakeup support")
  32 Signed-off-by: Sean Nyekjaer <sean@geanix.com>
  33 Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
  34 ---
  35  drivers/net/can/flexcan.c | 9 +++++++--
  36  1 file changed, 7 insertions(+), 2 deletions(-)
  37
  38 --- a/drivers/net/can/flexcan.c
  39 +++ b/drivers/net/can/flexcan.c
  40 @@ -137,8 +137,7 @@
  41         (FLEXCAN_ESR_ERR_BUS | FLEXCAN_ESR_ERR_STATE)
  42  #define FLEXCAN_ESR_ALL_INT \
  43         (FLEXCAN_ESR_TWRN_INT | FLEXCAN_ESR_RWRN_INT | \
  44 -        FLEXCAN_ESR_BOFF_INT | FLEXCAN_ESR_ERR_INT | \
  45 -        FLEXCAN_ESR_WAK_INT)
  46 +        FLEXCAN_ESR_BOFF_INT | FLEXCAN_ESR_ERR_INT)
  47
  48  /* FLEXCAN Bit Timing register (CBT) bits */
  49  #define FLEXCAN_CBT_BTF                        BIT(31)
  50 @@ -1056,6 +1055,12 @@ static irqreturn_t flexcan_irq(int irq,
  51
  52         reg_esr = priv->read(&regs->esr);
  53
  54 +       /* ACK wakeup interrupt */
  55 +       if (reg_esr & FLEXCAN_ESR_WAK_INT) {
  56 +               handled = IRQ_HANDLED;
  57 +               priv->write(reg_esr & FLEXCAN_ESR_WAK_INT, &regs->esr);
  58 +       }
  59 +
  60         /* ACK all bus error and state change IRQ sources */
  61         if (reg_esr & FLEXCAN_ESR_ALL_INT) {
  62                 handled = IRQ_HANDLED;