[PATCH v2 2/7] can: m_can: only handle active interrupts

[Marc Kleine-Budde <mkl@pengutronix.de>]

The M_CAN IP core has an Interrupt Register (IR) and an Interrupt
Enable (IE) register. An interrupt is triggered if at least 1 bit is
set in the bitwise and of IR and IE.

Depending on the configuration not all interrupts are enabled in the
IE register. However the m_can_rx_handler() IRQ handler looks at all
interrupts not just the enabled ones. This may lead to handling of not
activated interrupts.

Fix the problem and mask the irqstatus (IR register) with the
active_interrupts (cached value of IE register).

Fixes: e0d1f4816f2a ("can: m_can: add Bosch M_CAN controller support")
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/m_can/m_can.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index fe74dbd2c966..16b38e6c3985 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1057,6 +1057,7 @@ static int m_can_poll(struct napi_struct *napi, int quota)
 	u32 irqstatus;
 
 	irqstatus = cdev->irqstatus | m_can_read(cdev, M_CAN_IR);
+	irqstatus &= cdev->active_interrupts;
 
 	work_done = m_can_rx_handler(dev, quota, irqstatus);
 
@@ -1243,6 +1244,8 @@ static int m_can_interrupt_handler(struct m_can_classdev *cdev)
 	}
 
 	m_can_coalescing_update(cdev, ir);
+
+	ir &= cdev->active_interrupts;
 	if (!ir)
 		return IRQ_NONE;
 

-- 
2.51.0