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-rw-r--r--drivers/net/can/c_can/Kconfig7
-rw-r--r--drivers/net/can/c_can/c_can.c62
2 files changed, 55 insertions, 14 deletions
diff --git a/drivers/net/can/c_can/Kconfig b/drivers/net/can/c_can/Kconfig
index 61ffc12d8fd8..8ab7103d4f44 100644
--- a/drivers/net/can/c_can/Kconfig
+++ b/drivers/net/can/c_can/Kconfig
@@ -14,6 +14,13 @@ config CAN_C_CAN_PLATFORM
SPEAr1310 and SPEAr320 evaluation boards & TI (www.ti.com)
boards like am335x, dm814x, dm813x and dm811x.
+config CAN_C_CAN_STRICT_FRAME_ORDERING
+ bool "Force a strict RX CAN frame order (may cause frame loss)"
+ ---help---
+ The RX split buffer prevents packet reordering but can cause packet
+ loss. Only enable this option when you accept to lose CAN frames
+ in favour of getting the received CAN frames in the correct order.
+
config CAN_C_CAN_PCI
tristate "Generic PCI Bus based C_CAN/D_CAN driver"
depends on PCI
diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
index 09cb68772737..c1a8684ed1c8 100644
--- a/drivers/net/can/c_can/c_can.c
+++ b/drivers/net/can/c_can/c_can.c
@@ -791,18 +791,39 @@ static u32 c_can_adjust_pending(u32 pend)
return pend & ~((1 << lasts) - 1);
}
+static inline void c_can_rx_object_get(struct net_device *dev, u32 obj)
+{
+#ifdef CONFIG_CAN_C_CAN_STRICT_FRAME_ORDERING
+ if (obj < C_CAN_MSG_RX_LOW_LAST)
+ c_can_object_get(dev, IF_RX, obj, IF_COMM_RCV_LOW);
+ else
+#endif
+ c_can_object_get(dev, IF_RX, obj, IF_COMM_RCV_HIGH);
+}
+
+static inline void c_can_rx_finalize(struct net_device *dev,
+ struct c_can_priv *priv, u32 obj)
+{
+#ifdef CONFIG_CAN_C_CAN_STRICT_FRAME_ORDERING
+ if (obj < C_CAN_MSG_RX_LOW_LAST)
+ priv->rxmasked |= BIT(obj - 1);
+ else if (obj == C_CAN_MSG_RX_LOW_LAST) {
+ priv->rxmasked = 0;
+ /* activate all lower message objects */
+ c_can_activate_all_lower_rx_msg_obj(dev, IF_RX);
+ }
+#endif
+}
+
static int c_can_read_objects(struct net_device *dev, struct c_can_priv *priv,
u32 pend, int quota)
{
- u32 pkts = 0, ctrl, obj, mcmd;
+ u32 pkts = 0, ctrl, obj;
while ((obj = ffs(pend)) && quota > 0) {
pend &= ~BIT(obj - 1);
- mcmd = obj < C_CAN_MSG_RX_LOW_LAST ?
- IF_COMM_RCV_LOW : IF_COMM_RCV_HIGH;
-
- c_can_object_get(dev, IF_RX, obj, mcmd);
+ c_can_rx_object_get(dev, obj);
ctrl = priv->read_reg(priv, C_CAN_IFACE(MSGCTRL_REG, IF_RX));
if (ctrl & IF_MCONT_MSGLST) {
@@ -824,13 +845,7 @@ static int c_can_read_objects(struct net_device *dev, struct c_can_priv *priv,
/* read the data from the message object */
c_can_read_msg_object(dev, IF_RX, ctrl);
- if (obj < C_CAN_MSG_RX_LOW_LAST)
- priv->rxmasked |= BIT(obj - 1);
- else if (obj == C_CAN_MSG_RX_LOW_LAST) {
- priv->rxmasked = 0;
- /* activate all lower message objects */
- c_can_activate_all_lower_rx_msg_obj(dev, IF_RX);
- }
+ c_can_rx_finalize(dev, priv, obj);
pkts++;
quota--;
@@ -839,6 +854,16 @@ static int c_can_read_objects(struct net_device *dev, struct c_can_priv *priv,
return pkts;
}
+static inline u32 c_can_get_pending(struct c_can_priv *priv)
+{
+ u32 pend = priv->read_reg(priv, C_CAN_NEWDAT1_REG);
+
+#ifdef CONFIG_CAN_C_CAN_STRICT_FRAME_ORDERING
+ pend &= ~priv->rxmasked;
+#endif
+ return pend;
+}
+
/*
* theory of operation:
*
@@ -848,6 +873,8 @@ static int c_can_read_objects(struct net_device *dev, struct c_can_priv *priv,
* has arrived. To work-around this issue, we keep two groups of message
* objects whose partitioning is defined by C_CAN_MSG_OBJ_RX_SPLIT.
*
+ * If CONFIG_CAN_C_CAN_STRICT_FRAME_ORDERING = y
+ *
* To ensure in-order frame reception we use the following
* approach while re-activating a message object to receive further
* frames:
@@ -860,6 +887,14 @@ static int c_can_read_objects(struct net_device *dev, struct c_can_priv *priv,
* - if the current message object number is greater than
* C_CAN_MSG_RX_LOW_LAST then clear the NEWDAT bit of
* only this message object.
+ *
+ * This can cause packet loss!
+ *
+ * If CONFIG_CAN_C_CAN_STRICT_FRAME_ORDERING = n
+ *
+ * We clear the newdat bit right away.
+ *
+ * This can result in packet reordering when the readout is slow.
*/
static int c_can_do_rx_poll(struct net_device *dev, int quota)
{
@@ -875,8 +910,7 @@ static int c_can_do_rx_poll(struct net_device *dev, int quota)
while (quota > 0) {
if (!pend) {
- pend = priv->read_reg(priv, C_CAN_NEWDAT1_REG);
- pend &= ~priv->rxmasked;
+ pend = c_can_get_pending(priv);
if (!pend)
break;
/*
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