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Date: Thu, 19 Aug 2021 15:39:06 +0200
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net, kuba@...nel.org, linux-can@...r.kernel.org,
kernel@...gutronix.de, Matt Kline <matt@...bashing.io>,
Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH net-next 15/22] can: m_can: Batch FIFO writes during CAN transmit
From: Matt Kline <matt@...bashing.io>
Give FIFO writes the same treatment as reads to avoid fixed costs of
individual transfers on a slow bus (e.g., tcan4x5x).
Link: https://lore.kernel.org/r/20210817050853.14875-4-matt@bitbashing.io
Signed-off-by: Matt Kline <matt@...bashing.io>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
drivers/net/can/m_can/m_can.c | 61 +++++++++++++++--------------------
1 file changed, 26 insertions(+), 35 deletions(-)
diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index fbd32b48d265..2470c47b2e31 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -279,7 +279,7 @@ enum m_can_reg {
/* Message RAM Elements */
#define M_CAN_FIFO_ID 0x0
#define M_CAN_FIFO_DLC 0x4
-#define M_CAN_FIFO_DATA(n) (0x8 + ((n) << 2))
+#define M_CAN_FIFO_DATA 0x8
/* Rx Buffer Element */
/* R0 */
@@ -514,7 +514,7 @@ static int m_can_read_fifo(struct net_device *dev, u32 rxfs)
if (fifo_header.dlc & RX_BUF_BRS)
cf->flags |= CANFD_BRS;
- err = m_can_fifo_read(cdev, fgi, M_CAN_FIFO_DATA(0),
+ err = m_can_fifo_read(cdev, fgi, M_CAN_FIFO_DATA,
cf->data, DIV_ROUND_UP(cf->len, 4));
if (err)
goto out_fail;
@@ -1588,8 +1588,9 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
struct canfd_frame *cf = (struct canfd_frame *)cdev->tx_skb->data;
struct net_device *dev = cdev->net;
struct sk_buff *skb = cdev->tx_skb;
- u32 id, dlc, cccr, fdflags;
- int i, err;
+ struct id_and_dlc fifo_header;
+ u32 cccr, fdflags;
+ int err;
int putidx;
cdev->tx_skb = NULL;
@@ -1597,34 +1598,30 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
/* Generate ID field for TX buffer Element */
/* Common to all supported M_CAN versions */
if (cf->can_id & CAN_EFF_FLAG) {
- id = cf->can_id & CAN_EFF_MASK;
- id |= TX_BUF_XTD;
+ fifo_header.id = cf->can_id & CAN_EFF_MASK;
+ fifo_header.id |= TX_BUF_XTD;
} else {
- id = ((cf->can_id & CAN_SFF_MASK) << 18);
+ fifo_header.id = ((cf->can_id & CAN_SFF_MASK) << 18);
}
if (cf->can_id & CAN_RTR_FLAG)
- id |= TX_BUF_RTR;
+ fifo_header.id |= TX_BUF_RTR;
if (cdev->version == 30) {
netif_stop_queue(dev);
- /* message ram configuration */
- err = m_can_fifo_write(cdev, 0, M_CAN_FIFO_ID, &id, 1);
+ fifo_header.dlc = can_fd_len2dlc(cf->len) << 16;
+
+ /* Write the frame ID, DLC, and payload to the FIFO element. */
+ err = m_can_fifo_write(cdev, 0, M_CAN_FIFO_ID, &fifo_header, 2);
if (err)
goto out_fail;
- dlc = can_fd_len2dlc(cf->len) << 16;
- err = m_can_fifo_write(cdev, 0, M_CAN_FIFO_DLC, &dlc, 1);
+ err = m_can_fifo_write(cdev, 0, M_CAN_FIFO_DATA,
+ cf->data, DIV_ROUND_UP(cf->len, 4));
if (err)
goto out_fail;
- for (i = 0; i < cf->len; i += 4) {
- err = m_can_fifo_write(cdev, 0, M_CAN_FIFO_DATA(i / 4), cf->data + i, 1);
- if (err)
- goto out_fail;
- }
-
can_put_echo_skb(skb, dev, 0, 0);
if (cdev->can.ctrlmode & CAN_CTRLMODE_FD) {
@@ -1667,10 +1664,11 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
/* get put index for frame */
putidx = FIELD_GET(TXFQS_TFQPI_MASK,
m_can_read(cdev, M_CAN_TXFQS));
- /* Write ID Field to FIFO Element */
- err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_ID, &id, 1);
- if (err)
- goto out_fail;
+
+ /* Construct DLC Field, with CAN-FD configuration.
+ * Use the put index of the fifo as the message marker,
+ * used in the TX interrupt for sending the correct echo frame.
+ */
/* get CAN FD configuration of frame */
fdflags = 0;
@@ -1680,24 +1678,17 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
fdflags |= TX_BUF_BRS;
}
- /* Construct DLC Field. Also contains CAN-FD configuration
- * use put index of fifo as message marker
- * it is used in TX interrupt for
- * sending the correct echo frame
- */
- dlc = FIELD_PREP(TX_BUF_MM_MASK, putidx) |
+ 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_DLC, &dlc, 1);
+ err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_ID, &fifo_header, 2);
if (err)
goto out_fail;
- for (i = 0; i < cf->len; i += 4) {
- err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_DATA(i / 4),
- cf->data + i, 1);
- if (err)
- goto out_fail;
- }
+ err = m_can_fifo_write(cdev, putidx, M_CAN_FIFO_DATA,
+ cf->data, DIV_ROUND_UP(cf->len, 4));
+ if (err)
+ goto out_fail;
/* Push loopback echo.
* Will be looped back on TX interrupt based on message marker
--
2.32.0
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