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[PATCH 1/1] can: sja1000: clear interrupts on start

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From: Mirza Krak <mirza.krak@hostmobility.com>

According to SJA1000 data sheet error-warning (EI) interrupt is not
cleared by setting the controller in to reset-mode.

Then if we have the following case:
- system is suspended (echo mem > /sys/power/state) and SJA1000 is left
in operating state
- A bus error condition occurs which activates EI interrupt, system is
still suspended which means EI interrupt will be not be handled nor
cleared.

If the above two events occur, on resume there is no way to return the
SJA1000 to operating state, except to cycle power to it.

By simply reading the IR register on start we will clear any previous
conditions that could be present.

Signed-off-by: Mirza Krak <mirza.krak@hostmobility.com>
---
 drivers/net/can/sja1000/sja1000.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/can/sja1000/sja1000.c b/drivers/net/can/sja1000/sja1000.c
index 7b92e911a616..f10834be48a5 100644
--- a/drivers/net/can/sja1000/sja1000.c
+++ b/drivers/net/can/sja1000/sja1000.c
@@ -218,6 +218,9 @@ static void sja1000_start(struct net_device *dev)
 	priv->write_reg(priv, SJA1000_RXERR, 0x0);
 	priv->read_reg(priv, SJA1000_ECC);
 
+	/* clear interrupt flags */
+	priv->read_reg(priv, SJA1000_IR);
+
 	/* leave reset mode */
 	set_normal_mode(dev);
 }
-- 
2.1.0

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[PATCH 1/1] can: sja1000: clear interrupts on start Mirza Krak <mirza.krak@hostmobility.com> - 2015-11-10 15:00 +0100
  Re: [PATCH 1/1] can: sja1000: clear interrupts on start Marc Kleine-Budde <mkl@pengutronix.de> - 2015-11-11 09:10 +0100
    Re: [PATCH 1/1] can: sja1000: clear interrupts on start Mirza Krak <mirza.krak@hostmobility.com> - 2015-11-11 11:00 +0100
      Re: [PATCH 1/1] can: sja1000: clear interrupts on start Marc Kleine-Budde <mkl@pengutronix.de> - 2015-11-11 11:10 +0100
        Re: [PATCH 1/1] can: sja1000: clear interrupts on start Marc Kleine-Budde <mkl@pengutronix.de> - 2015-11-11 13:40 +0100
          Re: [PATCH 1/1] can: sja1000: clear interrupts on start Marc Kleine-Budde <mkl@pengutronix.de> - 2015-11-11 13:50 +0100
          Re: [PATCH 1/1] can: sja1000: clear interrupts on start Mirza Krak <mirza.krak@hostmobility.com> - 2015-11-11 13:50 +0100
            RE: [PATCH 1/1] can: sja1000: clear interrupts on start Christian Magnusson <Christian.Magnusson@semcon.com> - 2015-11-11 14:10 +0100
        Re: [PATCH 1/1] can: sja1000: clear interrupts on start Mirza Krak <mirza.krak@hostmobility.com> - 2015-11-11 13:40 +0100

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