can: tcan4x5x: tcan4x5x_init(): fix initialization - clear MRAM before entering Norma...

This patch prevents a potentially destructive race condition. The
device is fully operational on the bus after entering Normal Mode, so
zeroing the MRAM after entering this mode may lead to loss of
information, e.g. new received messages.

This patch fixes the problem by first initializing the MRAM, then
bringing the device into Normale Mode.

Fixes: 5443c226ba91 ("can: tcan4x5x: Add tcan4x5x driver to the kernel")
Link: https://lore.kernel.org/r/20210226163440.313628-1-torin@maxiluxsystems.com
Suggested-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Torin Cooper-Bennun <torin@maxiluxsystems.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/m_can/tcan4x5x-core.c b/drivers/net/can/m_can/tcan4x5x-core.c
index b7caec769ddb9b569c8376457cd3922337c1bf80..4147cecfbbd6dbd8e2207de82b728eed7dd2625d 100644 (file)
--- a/drivers/net/can/m_can/tcan4x5x-core.c
+++ b/drivers/net/can/m_can/tcan4x5x-core.c
@@ -237,14 +237,14 @@ static int tcan4x5x_init(struct m_can_classdev *cdev)
        if (ret)
                return ret;
 
+       /* Zero out the MCAN buffers */
+       m_can_init_ram(cdev);
+
        ret = regmap_update_bits(tcan4x5x->regmap, TCAN4X5X_CONFIG,
                                 TCAN4X5X_MODE_SEL_MASK, TCAN4X5X_MODE_NORMAL);
        if (ret)
                return ret;
 
-       /* Zero out the MCAN buffers */
-       m_can_init_ram(cdev);
-
        return ret;
 }