netdev - [PATCH v4 5/9] can: mcp251xfd: mcp251xfd_handle_rxif_ring

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Message-Id: <20240628-mcp251xfd-workaround-erratum-6-v4-5-53586f168524@pengutronix.de>
Date: Fri, 28 Jun 2024 23:40:29 +0200
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>, 
 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: Manivannan Sadhasivam <mani@...nel.org>, 
 Thomas Kopp <thomas.kopp@...rochip.com>, 
 Stefan Althöfer <Stefan.Althoefer@...ztec.com>, 
 kernel@...gutronix.de, linux-can@...r.kernel.org, netdev@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH v4 5/9] can: mcp251xfd: mcp251xfd_handle_rxif_ring_uinc():
 factor out in separate function

This is a preparation patch.

Sending the UINC messages followed by incrementing the tail pointer
will be called in more than one place in upcoming patches, so factor
this out into a separate function.

Also make mcp251xfd_handle_rxif_ring_uinc() safe to be called with a
"len" of 0.

Tested-by: Stefan Althöfer <Stefan.Althoefer@...ztec.com>
Tested-by: Thomas Kopp <thomas.kopp@...rochip.com>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/spi/mcp251xfd/mcp251xfd-rx.c | 48 ++++++++++++++++++----------
 1 file changed, 32 insertions(+), 16 deletions(-)

diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-rx.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-rx.c
index 6d66b97709b8..2c2b057b7ac7 100644
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-rx.c
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-rx.c
@@ -197,6 +197,37 @@ mcp251xfd_rx_obj_read(const struct mcp251xfd_priv *priv,
 	return err;
 }

+static int
+mcp251xfd_handle_rxif_ring_uinc(const struct mcp251xfd_priv *priv,
+				struct mcp251xfd_rx_ring *ring,
+				u8 len)
+{
+	int offset;
+	int err;
+
+	if (!len)
+		return 0;
+
+	/* Increment the RX FIFO tail pointer 'len' times in a
+	 * single SPI message.
+	 *
+	 * Note:
+	 * Calculate offset, so that the SPI transfer ends on
+	 * the last message of the uinc_xfer array, which has
+	 * "cs_change == 0", to properly deactivate the chip
+	 * select.
+	 */
+	offset = ARRAY_SIZE(ring->uinc_xfer) - len;
+	err = spi_sync_transfer(priv->spi,
+				ring->uinc_xfer + offset, len);
+	if (err)
+		return err;
+
+	ring->tail += len;
+
+	return 0;
+}
+
 static int
 mcp251xfd_handle_rxif_ring(struct mcp251xfd_priv *priv,
 			   struct mcp251xfd_rx_ring *ring)
@@ -210,8 +241,6 @@ mcp251xfd_handle_rxif_ring(struct mcp251xfd_priv *priv,
 		return err;

 	while ((len = mcp251xfd_get_rx_linear_len(ring))) {
-		int offset;
-
 		rx_tail = mcp251xfd_get_rx_tail(ring);

 		err = mcp251xfd_rx_obj_read(priv, ring, hw_rx_obj,
@@ -227,22 +256,9 @@ mcp251xfd_handle_rxif_ring(struct mcp251xfd_priv *priv,
 				return err;
 		}

-		/* Increment the RX FIFO tail pointer 'len' times in a
-		 * single SPI message.
-		 *
-		 * Note:
-		 * Calculate offset, so that the SPI transfer ends on
-		 * the last message of the uinc_xfer array, which has
-		 * "cs_change == 0", to properly deactivate the chip
-		 * select.
-		 */
-		offset = ARRAY_SIZE(ring->uinc_xfer) - len;
-		err = spi_sync_transfer(priv->spi,
-					ring->uinc_xfer + offset, len);
+		err = mcp251xfd_handle_rxif_ring_uinc(priv, ring, len);
 		if (err)
 			return err;
-
-		ring->tail += len;
 	}

 	return 0;

-- 
2.43.0