can: m_can: m_can_chip_config(): bring up interface in correct state

[ Upstream commit 4942c42fe1849e6d68dfb5b36ccba344a9fac016 ]

In some SoCs (observed on the STM32MP15) the M_CAN IP core keeps the
CAN state and CAN error counters over an internal reset cycle. An
external reset is not always possible, due to the shared reset with
the other CAN core. This caused the core not always be in Error Active
state when bringing up the controller.

Instead of always setting the CAN state to Error Active in
m_can_chip_config(), fix this by reading and decoding the Protocol
Status Regitser (PSR) and set the CAN state accordingly.

Fixes: e0d1f4816f2a ("can: m_can: add Bosch M_CAN controller support")
Reviewed-by: Markus Schneider-Pargmann <msp@baylibre.com>
Link: https://patch.msgid.link/20250929-m_can-fix-state-handling-v4-3-682b49b49d9a@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 8f663db386948690a99857076ab9bf55fe62fb13..a7e326faca8cac5a2949cce02f2dfc25730f37d1 100644 (file)
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1617,7 +1617,7 @@ static int m_can_start(struct net_device *dev)
        netdev_queue_set_dql_min_limit(netdev_get_tx_queue(cdev->net, 0),
                                       cdev->tx_max_coalesced_frames);
 
-       cdev->can.state = CAN_STATE_ERROR_ACTIVE;
+       cdev->can.state = m_can_state_get_by_psr(cdev);
 
        m_can_enable_all_interrupts(cdev);