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To:     "linux-can@vger.kernel.org" <linux-can@vger.kernel.org>
Cc:     Wolfgang Grandegger <wg@grandegger.com>,
        Marc Kleine-Budde <mkl@pengutronix.de>
From:   Mariusz Madej <mariusz.madej@xtrack.com>
Subject: [PATCH] can: m_can: reset IR_RF0L in message reception loop
Message-ID: <0710fbd2-4b88-21bf-88f7-0b97d7e7dc0b@xtrack.com>
Date:   Mon, 1 Mar 2021 22:21:27 +0100
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List-ID: <linux-can.vger.kernel.org>
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Message lost warning is reported in loop without interrupt reset. Besides
redundant log messages it may lead to serious performance problem, where
fifo gets full faster than next reception is scheduled by NAPI. This
patch fixes it.

Signed-off-by: Mariusz Madej <mariusz.madej@xtrack.com>
---
  drivers/net/can/m_can/m_can.c | 4 +++-
  1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 3752520a7..bd5539435 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -501,8 +501,10 @@ static int m_can_do_rx_poll(struct net_device *dev, int quota)
  	}
  
  	while ((rxfs & RXFS_FFL_MASK) && (quota > 0)) {
-		if (rxfs & RXFS_RFL)
+		if (rxfs & RXFS_RFL) {
  			netdev_warn(dev, "Rx FIFO 0 Message Lost\n");
+			m_can_write(cdev, M_CAN_IR, IR_RF0L);	
+		}
  
  		m_can_read_fifo(dev, rxfs);
  
-- 
2.20.1