Commit 81d192c2 authored by Marc Kleine-Budde's avatar Marc Kleine-Budde
Browse files

can: c_can: don't cache TX messages for C_CAN cores 

As Jacob noticed, the optimization introduced in 387da6bc ("can:
c_can: cache frames to operate as a true FIFO") doesn't properly work
on C_CAN, but on D_CAN IP cores. The exact reasons are still unknown.

For now disable caching if CAN frames in the TX path for C_CAN cores.

Fixes: 387da6bc ("can: c_can: cache frames to operate as a true FIFO")
Link: https://lore.kernel.org/all/20220928083354.1062321-1-mkl@pengutronix.de
Link: https://lore.kernel.org/all/15a8084b-9617-2da1-6704-d7e39d60643b@gmail.com


Reported-by: default avatarJacob Kroon <jacob.kroon@gmail.com>
Tested-by: default avatarJacob Kroon <jacob.kroon@gmail.com>
Cc: stable@vger.kernel.org # v5.15
Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent 44d70bb5

drivers/net/can/c_can/c_can.h

+15 −2
Original line number Diff line number Diff line
@@ -235,9 +235,22 @@ static inline u8 c_can_get_tx_tail(const struct c_can_tx_ring *ring) 
	return ring->tail & (ring->obj_num - 1);

}



static inline u8 c_can_get_tx_free(const struct c_can_tx_ring *ring)

static inline u8 c_can_get_tx_free(const struct c_can_priv *priv,

				   const struct c_can_tx_ring *ring)

{

	u8 head = c_can_get_tx_head(ring);

	u8 tail = c_can_get_tx_tail(ring);



	if (priv->type == BOSCH_D_CAN)

		return ring->obj_num - (ring->head - ring->tail);



	/* This is not a FIFO. C/D_CAN sends out the buffers

	 * prioritized. The lowest buffer number wins.

	 */

	if (head < tail)

		return 0;



	return ring->obj_num - head;

}



#endif /* C_CAN_H */

drivers/net/can/c_can/c_can_main.c

+5 −6
Original line number Diff line number Diff line
@@ -429,7 +429,7 @@ static void c_can_setup_receive_object(struct net_device *dev, int iface, 
static bool c_can_tx_busy(const struct c_can_priv *priv,

			  const struct c_can_tx_ring *tx_ring)

{

	if (c_can_get_tx_free(tx_ring) > 0)

	if (c_can_get_tx_free(priv, tx_ring) > 0)

		return false;



	netif_stop_queue(priv->dev);
@@ -437,7 +437,7 @@ static bool c_can_tx_busy(const struct c_can_priv *priv, 
	/* Memory barrier before checking tx_free (head and tail) */

	smp_mb();



	if (c_can_get_tx_free(tx_ring) == 0) {

	if (c_can_get_tx_free(priv, tx_ring) == 0) {

		netdev_dbg(priv->dev,

			   "Stopping tx-queue (tx_head=0x%08x, tx_tail=0x%08x, len=%d).\n",

			   tx_ring->head, tx_ring->tail,
@@ -465,7 +465,7 @@ static netdev_tx_t c_can_start_xmit(struct sk_buff *skb, 


	idx = c_can_get_tx_head(tx_ring);

	tx_ring->head++;

	if (c_can_get_tx_free(tx_ring) == 0)

	if (c_can_get_tx_free(priv, tx_ring) == 0)

		netif_stop_queue(dev);



	if (idx < c_can_get_tx_tail(tx_ring))
@@ -748,7 +748,7 @@ static void c_can_do_tx(struct net_device *dev) 
		return;



	tx_ring->tail += pkts;

	if (c_can_get_tx_free(tx_ring)) {

	if (c_can_get_tx_free(priv, tx_ring)) {

		/* Make sure that anybody stopping the queue after

		 * this sees the new tx_ring->tail.

		 */
@@ -760,8 +760,7 @@ static void c_can_do_tx(struct net_device *dev) 
	stats->tx_packets += pkts;



	tail = c_can_get_tx_tail(tx_ring);



	if (tail == 0) {

	if (priv->type == BOSCH_D_CAN && tail == 0) {

		u8 head = c_can_get_tx_head(tx_ring);



		/* Start transmission for all cached messages */