linux-kernel - [PATCH can-next 14/21] can: rockchip_canfd: implement workaround for erratum 12

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Message-Id: <20240729-rockchip-canfd-v1-14-fa1250fd6be3@pengutronix.de>
Date: Mon, 29 Jul 2024 15:05:45 +0200
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: kernel@...gutronix.de, 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>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Heiko Stuebner <heiko@...ech.de>, 
 Philipp Zabel <p.zabel@...gutronix.de>, 
 Elaine Zhang <zhangqing@...k-chips.com>, 
 David Jander <david.jander@...tonic.nl>
Cc: linux-can@...r.kernel.org, netdev@...r.kernel.org, 
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH can-next 14/21] can: rockchip_canfd: implement workaround
 for erratum 12

The rk3568 CAN-FD errata sheet as of Tue 07 Nov 2023 11:25:31 +08:00
says:

| A dominant bit at the third bit of the intermission may cause a
| transmission error.
|
| When sampling the third bit of the intermission as a dominant bit, if
| tx_req is configured to transmit extended frames at this time, the
| extended frame may be sent to the bus in the format of a standard
| frame. The extended frame will be sent as a standard frame and will not
| result in error frames

Turn on "Interframe Spaceing RX Mode" only during TX to work around
erratum 12, according to rock-chip:

| Spaceing RX Mode = 1, the third Bit between frames cannot receive
| and send, and the fourth Bit begins to receive and send.
|
| Spaceing RX Mode = 0, allowing the third Bit between frames to
| receive and send.

Message-ID: <be72939f-0a9e-0608-dfff-7b0096a26eba@...k-chips.com>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/rockchip/rockchip_canfd-tx.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/can/rockchip/rockchip_canfd-tx.c b/drivers/net/can/rockchip/rockchip_canfd-tx.c
index fcf7d8f07118..43d011ab6455 100644
--- a/drivers/net/can/rockchip/rockchip_canfd-tx.c
+++ b/drivers/net/can/rockchip/rockchip_canfd-tx.c
@@ -11,7 +11,14 @@
 static void rkcanfd_start_xmit_write_cmd(const struct rkcanfd_priv *priv,
 					 const u32 reg_cmd)
 {
+	if (priv->devtype_data.quirks & RKCANFD_QUIRK_RK3568_ERRATUM_12)
+		rkcanfd_write(priv, RKCANFD_REG_MODE, priv->reg_mode_default |
+			      RKCANFD_REG_MODE_SPACE_RX_MODE);
+
 	rkcanfd_write(priv, RKCANFD_REG_CMD, reg_cmd);
+
+	if (priv->devtype_data.quirks & RKCANFD_QUIRK_RK3568_ERRATUM_12)
+		rkcanfd_write(priv, RKCANFD_REG_MODE, priv->reg_mode_default);
 }

 void rkcanfd_xmit_retry(struct rkcanfd_priv *priv)

-- 
2.43.0