can: xilinx_can: xcanfd_rx(): fix FSR register handling in the RX path

After commit c223da689324 ("can: xilinx_can: Add support for CANFD FD
frames") the driver is updating the FSR IRI index multiple times (i.e in
xcanfd_rx() and xcan_rx_fifo_get_next_frame()), It should be updated
once per RX packet. This patch fixes this issue, also this patch removes
the unnecessary fsr register checks in xcanfd_rx() API.

Fixes: c223da6 ("can: xilinx_can: Add support for CANFD FD frames")
Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Reviewed-by: Shubhrajyoti Datta <Shubhrajyoti.datta@xilinx.com>
Signed-off-by: Appana Durga Kedareswara rao <appana.durga.rao@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/xilinx_can.c b/drivers/net/can/xilinx_can.c
index 161bb5e..2e5cbff 100644 (file)
--- a/drivers/net/can/xilinx_can.c
+++ b/drivers/net/can/xilinx_can.c
@@ -808,91 +808,78 @@ static int xcanfd_rx(struct net_device *ndev, int frame_base)
        u32 id_xcan, dlc, data[2] = {0, 0}, dwindex = 0, i, fsr, readindex;
 
        fsr = priv->read_reg(priv, XCAN_FSR_OFFSET);
-       if (fsr & XCAN_FSR_FL_MASK) {
-               readindex = fsr & XCAN_FSR_RI_MASK;
-               id_xcan = priv->read_reg(priv,
-                                        XCAN_FRAME_ID_OFFSET(frame_base));
-               dlc = priv->read_reg(priv, XCAN_FRAME_DLC_OFFSET(frame_base));
-               if (dlc & XCAN_DLCR_EDL_MASK)
-                       skb = alloc_canfd_skb(ndev, &cf);
-               else
-                       skb = alloc_can_skb(ndev, (struct can_frame **)&cf);
+       readindex = fsr & XCAN_FSR_RI_MASK;
+       id_xcan = priv->read_reg(priv, XCAN_FRAME_ID_OFFSET(frame_base));
+       dlc = priv->read_reg(priv, XCAN_FRAME_DLC_OFFSET(frame_base));
+       if (dlc & XCAN_DLCR_EDL_MASK)
+               skb = alloc_canfd_skb(ndev, &cf);
+       else
+               skb = alloc_can_skb(ndev, (struct can_frame **)&cf);
 
-               if (unlikely(!skb)) {
-                       stats->rx_dropped++;
-                       return 0;
-               }
+       if (unlikely(!skb)) {
+               stats->rx_dropped++;
+               return 0;
+       }
 
-               /* Change Xilinx CANFD data length format to socketCAN data
-                * format
-                */
-               if (dlc & XCAN_DLCR_EDL_MASK)
-                       cf->len = can_dlc2len((dlc & XCAN_DLCR_DLC_MASK) >>
+       /* Change Xilinx CANFD data length format to socketCAN data
+        * format
+        */
+       if (dlc & XCAN_DLCR_EDL_MASK)
+               cf->len = can_dlc2len((dlc & XCAN_DLCR_DLC_MASK) >>
+                                 XCAN_DLCR_DLC_SHIFT);
+       else
+               cf->len = get_can_dlc((dlc & XCAN_DLCR_DLC_MASK) >>
                                          XCAN_DLCR_DLC_SHIFT);
-               else
-                       cf->len = get_can_dlc((dlc & XCAN_DLCR_DLC_MASK) >>
-                                                 XCAN_DLCR_DLC_SHIFT);
-
-               /* Change Xilinx CAN ID format to socketCAN ID format */
-               if (id_xcan & XCAN_IDR_IDE_MASK) {
-                       /* The received frame is an Extended format frame */
-                       cf->can_id = (id_xcan & XCAN_IDR_ID1_MASK) >> 3;
-                       cf->can_id |= (id_xcan & XCAN_IDR_ID2_MASK) >>
-                                       XCAN_IDR_ID2_SHIFT;
-                       cf->can_id |= CAN_EFF_FLAG;
-                       if (id_xcan & XCAN_IDR_RTR_MASK)
-                               cf->can_id |= CAN_RTR_FLAG;
-               } else {
-                       /* The received frame is a standard format frame */
-                       cf->can_id = (id_xcan & XCAN_IDR_ID1_MASK) >>
-                                       XCAN_IDR_ID1_SHIFT;
-                       if (!(dlc & XCAN_DLCR_EDL_MASK) && (id_xcan &
-                                               XCAN_IDR_SRR_MASK))
-                               cf->can_id |= CAN_RTR_FLAG;
-               }
 
-               /* Check the frame received is FD or not*/
-               if (dlc & XCAN_DLCR_EDL_MASK) {
-                       for (i = 0; i < cf->len; i += 4) {
-                               if (priv->devtype.flags & XCAN_FLAG_CANFD_2)
-                                       data[0] = priv->read_reg(priv,
+       /* Change Xilinx CAN ID format to socketCAN ID format */
+       if (id_xcan & XCAN_IDR_IDE_MASK) {
+               /* The received frame is an Extended format frame */
+               cf->can_id = (id_xcan & XCAN_IDR_ID1_MASK) >> 3;
+               cf->can_id |= (id_xcan & XCAN_IDR_ID2_MASK) >>
+                               XCAN_IDR_ID2_SHIFT;
+               cf->can_id |= CAN_EFF_FLAG;
+               if (id_xcan & XCAN_IDR_RTR_MASK)
+                       cf->can_id |= CAN_RTR_FLAG;
+       } else {
+               /* The received frame is a standard format frame */
+               cf->can_id = (id_xcan & XCAN_IDR_ID1_MASK) >>
+                               XCAN_IDR_ID1_SHIFT;
+               if (!(dlc & XCAN_DLCR_EDL_MASK) && (id_xcan &
+                                       XCAN_IDR_SRR_MASK))
+                       cf->can_id |= CAN_RTR_FLAG;
+       }
+
+       /* Check the frame received is FD or not*/
+       if (dlc & XCAN_DLCR_EDL_MASK) {
+               for (i = 0; i < cf->len; i += 4) {
+                       if (priv->devtype.flags & XCAN_FLAG_CANFD_2)
+                               data[0] = priv->read_reg(priv,
                                        (XCAN_RXMSG_2_FRAME_OFFSET(readindex) +
                                        (dwindex * XCANFD_DW_BYTES)));
-                               else
-                                       data[0] = priv->read_reg(priv,
+                       else
+                               data[0] = priv->read_reg(priv,
                                        (XCAN_RXMSG_FRAME_OFFSET(readindex) +
-                                               (dwindex * XCANFD_DW_BYTES)));
-                               *(__be32 *)(cf->data + i) =
-                                               cpu_to_be32(data[0]);
-                               dwindex++;
-                       }
-               } else {
-                       for (i = 0; i < cf->len; i += 4) {
-                               if (priv->devtype.flags & XCAN_FLAG_CANFD_2)
-                                       data[0] = priv->read_reg(priv,
-                                               XCAN_RXMSG_2_FRAME_OFFSET(readindex) + i);
-                               else
-                                       data[0] = priv->read_reg(priv,
-                                               XCAN_RXMSG_FRAME_OFFSET(readindex) + i);
-                               *(__be32 *)(cf->data + i) =
-                                               cpu_to_be32(data[0]);
-                       }
+                                       (dwindex * XCANFD_DW_BYTES)));
+                       *(__be32 *)(cf->data + i) = cpu_to_be32(data[0]);
+                       dwindex++;
+               }
+       } else {
+               for (i = 0; i < cf->len; i += 4) {
+                       if (priv->devtype.flags & XCAN_FLAG_CANFD_2)
+                               data[0] = priv->read_reg(priv,
+                                       XCAN_RXMSG_2_FRAME_OFFSET(readindex) +
+                                                                 i);
+                       else
+                               data[0] = priv->read_reg(priv,
+                                       XCAN_RXMSG_FRAME_OFFSET(readindex) + i);
+                       *(__be32 *)(cf->data + i) = cpu_to_be32(data[0]);
                }
-               /* Update FSR Register so that next packet will save to
-                * buffer
-                */
-               fsr = priv->read_reg(priv, XCAN_FSR_OFFSET);
-               fsr |= XCAN_FSR_IRI_MASK;
-               priv->write_reg(priv, XCAN_FSR_OFFSET, fsr);
-               fsr = priv->read_reg(priv, XCAN_FSR_OFFSET);
-               stats->rx_bytes += cf->len;
-               stats->rx_packets++;
-               netif_receive_skb(skb);
-
-               return 1;
        }
-       /* If FSR Register is not updated with fill level */
-       return 0;
+       stats->rx_bytes += cf->len;
+       stats->rx_packets++;
+       netif_receive_skb(skb);
+
+       return 1;
 }
 
 /**