Hi Oliver,

Thank you for your review.

-----Original Message-----
From: Oliver Hartkopp [mailto:socketcan@hartkopp.net]
Sent: 2017年3月6日 3:34
To: Wenyou Yang - A41535 <redacted>; Wolfgang
Grandegger [off-list ref]; Marc Kleine-Budde [off-list ref]
Cc: Alexandre Belloni <redacted>; Florian Fainelli
[off-list ref]; Quentin Schulz [off-list ref];
Wenyou Yang - A41535 [off-list ref]; Nicolas Ferre
[off-list ref]; linux-can@vger.kernel.org; netdev@vger.kernel.org;
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] can: m_can: support transmit frame in CAN FD format

The patch has some issues:

On 03/03/2017 06:33 AM, Wenyou Yang wrote:

quoted

Add support to transmit the frame in the CAN FD format and with the
bit rate switching.

This is a misleading comment.

"can: m_can: support transmit frame in CAN FD format"
is misleading too. You were able to send CAN FD frames before.

This patch enables the transmission of CAN FD frames on M_CAN IP cores  >=
v3.1.x, right?

The revision of M_CAN IP on SAMA5D2 is 3.1.0 (CREL = 0x31040730).

So this should be mentioned properly.

quoted

Tested on SAMA5D2 Xplained board.

Tested on which M_CAN IP core revision would be useful here.

quoted

Signed-off-by: Wenyou Yang <redacted>
---
The testing is based on
[RESEND PATCH 1/1] can: m_can: fix bitrate setup on latest silicon
http://lkml.iu.edu/hypermail/linux/kernel/1702.1/05347.html

 drivers/net/can/m_can/m_can.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c

b/drivers/net/can/m_can/m_can.c index 195f15edb32e..9ef9b337d25b
100644

--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c

@@ -266,8 +266,12 @@ enum m_can_mram_cfg {

 /* Tx Buffer Element */
 /* R0 */
+#define TX_BUF_ESI		BIT(31)
 #define TX_BUF_XTD		BIT(30)
 #define TX_BUF_RTR		BIT(29)
+#define TX_BUF_EFC		BIT(23)
+#define TX_BUF_EDL		BIT(21)

This bit is named FDF (FD Format bit).

It has to be:

#define TX_BUF_FDF		BIT(21)

quoted

+#define TX_BUF_BRS		BIT(20)

 /* address offset and element number for each FIFO/Buffer in the
Message RAM */  struct mram_cfg { @@ -884,7 +888,7 @@ static void
m_can_chip_config(struct net_device *dev)
 	}

 	if (priv->can.ctrlmode & CAN_CTRLMODE_FD)
-		cccr |= CCCR_CME_CANFD_BRS << CCCR_CME_SHIFT;
+		cccr |= (CCCR_CME_CANFD_BRS | CCCR_CME_CANFD) <<

CCCR_CME_SHIFT;

quoted

 	m_can_write(priv, M_CAN_CCCR, cccr);
 	m_can_write(priv, M_CAN_TEST, test); @@ -1047,6 +1051,7 @@ static
netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
 	struct canfd_frame *cf = (struct canfd_frame *)skb->data;
 	u32 id, cccr;
 	int i;
+	u32 dlc;

 	if (can_dropped_invalid_skb(dev, skb))
 		return NETDEV_TX_OK;

@@ -1065,7 +1070,6 @@ static netdev_tx_t m_can_start_xmit(struct

sk_buff *skb,

 	/* message ram configuration */
 	m_can_fifo_write(priv, 0, M_CAN_FIFO_ID, id);
-	m_can_fifo_write(priv, 0, M_CAN_FIFO_DLC, can_len2dlc(cf->len) << 16);

 	for (i = 0; i < cf->len; i += 4)
 		m_can_fifo_write(priv, 0, M_CAN_FIFO_DATA(i / 4), @@ -

1073,20

quoted

+1077,29 @@ static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,

 	can_put_echo_skb(skb, dev, 0);

+	dlc = can_len2dlc(cf->len) << 16;
+
 	if (priv->can.ctrlmode & CAN_CTRLMODE_FD) {
 		cccr = m_can_read(priv, M_CAN_CCCR);
 		cccr &= ~(CCCR_CMR_MASK << CCCR_CMR_SHIFT);
 		if (can_is_canfd_skb(skb)) {
-			if (cf->flags & CANFD_BRS)
+			dlc |= TX_BUF_EDL;

dito FDF

quoted

+			if (cf->flags & CANFD_ESI)
+				dlc |= TX_BUF_ESI;
+			if (cf->flags & CANFD_BRS) {
+				dlc |= TX_BUF_BRS;
 				cccr |= CCCR_CMR_CANFD_BRS <<

CCCR_CMR_SHIFT;

quoted

-			else
+			} else {
 				cccr |= CCCR_CMR_CANFD <<

CCCR_CMR_SHIFT;

quoted

+			}
 		} else {
 			cccr |= CCCR_CMR_CAN << CCCR_CMR_SHIFT;
 		}
 		m_can_write(priv, M_CAN_CCCR, cccr);
 	}

+	m_can_fifo_write(priv, 0, M_CAN_FIFO_DLC, dlc);
+
 	/* enable first TX buffer to start transfer  */
 	m_can_write(priv, M_CAN_TXBTIE, 0x1);
 	m_can_write(priv, M_CAN_TXBAR, 0x1);

Beside the documentation and the wrong bit naming the patch looks ok.
Please resend.

I will send a version 2. Thanks

Regards,
Oliver

Best Regards,
Wenyou Yang