can: mcp251xfd: mcp251xfd_ring_init(): check TX-coalescing configuration

When changing the interface from CAN-CC to CAN-FD mode the old
coalescing parameters are re-used. This might cause problem, as the
configured parameters are too big for CAN-FD mode.

During testing an invalid TX coalescing configuration has been seen.
The problem should be been fixed in the previous patch, but add a
safeguard here to ensure that the number of TEF coalescing buffers (if
configured) is exactly the half of all TEF buffers.

Link: https://lore.kernel.org/all/20240805-mcp251xfd-fix-ringconfig-v1-2-72086f0ca5ee@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-ring.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-ring.c
index f72582d4d3e8e249a41633b2a93f8a9bc2d90f88..83c18035b2a24dc30695c4aa3d18c7a3b32af3db 100644 (file)
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-ring.c
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-ring.c
@@ -290,7 +290,7 @@ int mcp251xfd_ring_init(struct mcp251xfd_priv *priv)
        const struct mcp251xfd_rx_ring *rx_ring;
        u16 base = 0, ram_used;
        u8 fifo_nr = 1;
-       int i;
+       int err = 0, i;
 
        netdev_reset_queue(priv->ndev);
 
@@ -386,10 +386,18 @@ int mcp251xfd_ring_init(struct mcp251xfd_priv *priv)
                netdev_err(priv->ndev,
                           "Error during ring configuration, using more RAM (%u bytes) than available (%u bytes).\n",
                           ram_used, MCP251XFD_RAM_SIZE);
-               return -ENOMEM;
+               err = -ENOMEM;
        }
 
-       return 0;
+       if (priv->tx_obj_num_coalesce_irq &&
+           priv->tx_obj_num_coalesce_irq * 2 != priv->tx->obj_num) {
+               netdev_err(priv->ndev,
+                          "Error during ring configuration, number of TEF coalescing buffers (%u) must be half of TEF buffers (%u).\n",
+                          priv->tx_obj_num_coalesce_irq, priv->tx->obj_num);
+               err = -EINVAL;
+       }
+
+       return err;
 }
 
 void mcp251xfd_ring_free(struct mcp251xfd_priv *priv)