netdev - [PATCH 2/2] can: mcp251xfd: mcp251xfd_ring_init(): check TX-coalescing configuration

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Message-Id: <20240805-mcp251xfd-fix-ringconfig-v1-2-72086f0ca5ee@pengutronix.de>
Date: Mon, 05 Aug 2024 18:23:21 +0200
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>, 
 Thomas Kopp <thomas.kopp@...rochip.com>, 
 Vincent Mailhol <mailhol.vincent@...adoo.fr>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: linux-can@...r.kernel.org, netdev@...r.kernel.org, 
 linux-kernel@...r.kernel.org, kernel@...gutronix.de, 
 Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH 2/2] 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.

Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/spi/mcp251xfd/mcp251xfd-ring.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-ring.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-ring.c
index f72582d4d3e8..83c18035b2a2 100644
--- 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)

-- 
2.43.0