Re: [RESEND PATCH 4/4] can: c_can: cache frames to operate as a true FIFO

On 05.08.2021 22:12:18, Dario Binacchi wrote:

quoted

quoted

diff --git a/drivers/net/can/c_can/c_can.h b/drivers/net/can/c_can/c_can.h
index 8fe7e2138620..fc499a70b797 100644
--- a/drivers/net/can/c_can/c_can.h
+++ b/drivers/net/can/c_can/c_can.h
+static inline u8 c_can_get_tx_free(const struct c_can_tx_ring *ring)
+{
+	return ring->obj_num - (ring->head - ring->tail);
+}
+
 #endif /* C_CAN_H */
diff --git a/drivers/net/can/c_can/c_can_main.c b/drivers/net/can/c_can/c_can_main.c
index 451ac9a9586a..4c061fef002c 100644
--- a/drivers/net/can/c_can/c_can_main.c
+++ b/drivers/net/can/c_can/c_can_main.c

@@ -427,20 +427,6 @@ static void c_can_setup_receive_object(struct net_device *dev, int iface,
 	c_can_object_put(dev, iface, obj, IF_COMM_RCV_SETUP);
 }
 
-static u8 c_can_get_tx_free(const struct c_can_tx_ring *ring)
-{
-	u8 head = c_can_get_tx_head(ring);
-	u8 tail = c_can_get_tx_tail(ring);
-
-	/* 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;
-}
-

Can you move that change into patch 3?

Patch 3 adds the ring transmission algorithm without compromising the
message transmission order. This is not a FIFO.

Right, thanks!

C/D_CAN controller sends out the buffers prioritized. The lowest
buffer number wins, so moving the change into patch 3 may not
guarantee the transmission order. In patch 3, however, I will move
c_can_get_tx_free() from c_can_main.c to c_can.h, so that in patch 4
it will be clearer how the routine has changed.

The updated patch looks much nicer now, thanks!

Marc

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