net: can: xilinx_can: fix extended frame handling

Using IDR_SRR in RXFIFO_ID to test for the presence of data is only
valid for standard frames. For extended frames the bit is always 1 and
IDR_RTR should be used instead. This patch switches the check to use
CAN_RTR_FLAG which is correctly set when reading the ID.

The patch also changes the DW1/DW2 to be read unconditionally, since
this is necessary to remove the frame from the RXFIFO.

Signed-off-by: Jeppe Ledet-Pedersen <jlp@gomspace.com>
Acked-by: Kedareswara rao Appana <appanad@xilinx.com>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/net/can/xilinx_can.c b/drivers/net/can/xilinx_can.c
index 6bddfe062b51..fc55e8e0351d 100644
--- a/drivers/net/can/xilinx_can.c
+++ b/drivers/net/can/xilinx_can.c
@@ -509,10 +509,11 @@ static int xcan_rx(struct net_device *ndev)
                         cf->can_id |= CAN_RTR_FLAG;
         }
 
-        if (!(id_xcan & XCAN_IDR_SRR_MASK)) {
-                data[0] = priv->read_reg(priv, XCAN_RXFIFO_DW1_OFFSET);
-                data[1] = priv->read_reg(priv, XCAN_RXFIFO_DW2_OFFSET);
+        /* DW1/DW2 must always be read to remove message from RXFIFO */
+        data[0] = priv->read_reg(priv, XCAN_RXFIFO_DW1_OFFSET);
+        data[1] = priv->read_reg(priv, XCAN_RXFIFO_DW2_OFFSET);
 
+        if (!(cf->can_id & CAN_RTR_FLAG)) {
                 /* Change Xilinx CAN data format to socketCAN data format */
                 if (cf->can_dlc > 0)
                         *(__be32 *)(cf->data) = cpu_to_be32(data[0]);