From: Matt Kline <matt@bitbashing.io>
To: Wolfgang Grandegger <wg@grandegger.com>,
Marc Kleine-Budde <mkl@pengutronix.de>
Cc: Matt Kline <matt@bitbashing.io>, linux-can@vger.kernel.org
Subject: [PATCH v3 3/3] can: m_can: Batch FIFO writes during CAN transmit
Date: Mon, 16 Aug 2021 22:08:53 -0700 [thread overview]
Message-ID: <20210817050853.14875-4-matt@bitbashing.io> (raw)
In-Reply-To: <20210817050853.14875-1-matt@bitbashing.io>
Give FIFO writes the same treatment as reads to avoid fixed costs of
individual transfers on a slow bus (e.g., tcan4x5x).
Signed-off-by: Matt Kline <matt@bitbashing.io>
---
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 85d6cd03bff1..b0e20c7d596c 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -278,7 +278,7 @@ 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 */
@@ -510,7 +510,7 @@ 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;
@@ -1593,8 +1593,9 @@ 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;
@@ -1602,34 +1603,30 @@ 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) {
@@ -1672,10 +1669,11 @@ 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;
@@ -1685,24 +1683,17 @@ 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
prev parent reply other threads:[~2021-08-17 5:09 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-17 5:08 [PATCH v3 0/3] can: m_can: Merge FIFO ops to increase throughput Matt Kline
2021-08-17 5:08 ` [PATCH v3 1/3] can: m_can: Disable IRQs on FIFO bus errors Matt Kline
2021-08-19 11:30 ` Marc Kleine-Budde
2021-08-17 5:08 ` [PATCH v3 2/3] can: m_can: Batch FIFO reads during CAN receive Matt Kline
2021-08-19 11:45 ` Marc Kleine-Budde
2021-09-16 12:04 ` Aswath Govindraju
2021-09-27 8:25 ` Matt Kline
2021-08-17 5:08 ` Matt Kline [this message]
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