From:   Markus Schneider-Pargmann <msp@baylibre.com>
To:     Marc Kleine-Budde <mkl@pengutronix.de>,
        Chandrasekar Ramakrishnan <rcsekar@samsung.com>,
        Wolfgang Grandegger <wg@grandegger.com>
Cc:     Vincent MAILHOL <mailhol.vincent@wanadoo.fr>,
        linux-can@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Markus Schneider-Pargmann <msp@baylibre.com>
Subject: [PATCH v2 08/18] can: m_can: Write transmit header and data in one transaction
Date:   Wed, 25 Jan 2023 20:50:49 +0100
Message-Id: <20230125195059.630377-9-msp@baylibre.com>
In-Reply-To: <20230125195059.630377-1-msp@baylibre.com>
References: <20230125195059.630377-1-msp@baylibre.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Combine header and data before writing to the transmit fifo to reduce
the overhead for peripheral chips.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
---
 drivers/net/can/m_can/m_can.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 78f6ed744c36..440bc0536951 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1681,6 +1681,7 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
 		m_can_write(cdev, M_CAN_TXBAR, 0x1);
 		/* End of xmit function for version 3.0.x */
 	} else {
+		char buf[TXB_ELEMENT_SIZE];
 		/* Transmit routine for version >= v3.1.x */
 
 		txfqs = m_can_read(cdev, M_CAN_TXFQS);
@@ -1720,12 +1721,11 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
 		fifo_header.dlc = FIELD_PREP(TX_BUF_MM_MASK, putidx) |
 			FIELD_PREP(TX_BUF_DLC_MASK, can_fd_len2dlc(cf->len)) |
 			fdflags | TX_BUF_EFC;
-		err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_ID, &fifo_header, 2);
-		if (err)
-			goto out_fail;
+		memcpy(buf, &fifo_header, 8);
+		memcpy(&buf[8], &cf->data, cf->len);
 
-		err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_DATA,
-				       cf->data, DIV_ROUND_UP(cf->len, 4));
+		err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_ID,
+				       buf, 8 + DIV_ROUND_UP(cf->len, 4));
 		if (err)
 			goto out_fail;
 
-- 
2.39.0