From: Fedor Ross <fedor.ross@xxxxxxx>
Make `MCP251XFD_POLL_TIMEOUT_US` timeout calculation dynamic. Use
maximum of 1ms (arbitrarily chosen during driver development) and
bit time of one full CANFD frame including bit stuffing and bus idle
condition sample cycles, at the current bitrate. This seems to be
necessary when configuring low bit rates like 10 Kbit/s for example.
Otherwise during polling for the CAN controller to enter
'Normal CAN 2.0 mode' the timeout limit is exceeded and the
configuration fails with:
$ ip link set dev can1 up type can bitrate 10000
[ 731.911072] mcp251xfd spi2.1 can1: Controller failed to enter mode CAN 2.0 Mode (6) and stays in Configuration Mode (4) (con=0x068b0760, osc=0x00000468).
[ 731.927192] mcp251xfd spi2.1 can1: CRC read error at address 0x0e0c (length=4, data=00 00 00 00, CRC=0x0000) retrying.
[ 731.938101] A link change request failed with some changes committed already. Interface can1 may have been left with an inconsistent configuration, please check.
RTNETLINK answers: Connection timed out
Fixes: 55e5b97f003e ("can: mcp25xxfd: add driver for Microchip MCP25xxFD SPI CAN")
Signed-off-by: Fedor Ross <fedor.ross@xxxxxxx>
Signed-off-by: Marek Vasut <marex@xxxxxxx>
---
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: Liam Girdwood <lgirdwood@xxxxxxxxx>
Cc: Manivannan Sadhasivam <mani@xxxxxxxxxx>
Cc: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Cc: Marek Vasut <marex@xxxxxxx>
Cc: Mark Brown <broonie@xxxxxxxxxx>
Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
Cc: Thomas Kopp <thomas.kopp@xxxxxxxxxxxxx>
Cc: Wolfgang Grandegger <wg@xxxxxxxxxxxxxx>
Cc: linux-can@xxxxxxxxxxxxxxx
---
V2: - Add macros for CAN_BIT_STUFFING_OVERHEAD and CAN_IDLE_CONDITION_SAMPLES
(thanks Thomas, but please double check the comments)
- Update commit message
---
drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c | 8 +++++++-
drivers/net/can/spi/mcp251xfd/mcp251xfd.h | 9 +++++++++
2 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
index 68df6d4641b5c..207bcd5bf795b 100644
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
@@ -227,6 +227,7 @@ static int
__mcp251xfd_chip_set_mode(const struct mcp251xfd_priv *priv,
const u8 mode_req, bool nowait)
{
+ const struct can_bittiming *bt = &priv->can.bittiming;
u32 con = 0, con_reqop, osc = 0;
u8 mode;
int err;
@@ -251,7 +252,12 @@ __mcp251xfd_chip_set_mode(const struct mcp251xfd_priv *priv,
FIELD_GET(MCP251XFD_REG_CON_OPMOD_MASK,
con) == mode_req,
MCP251XFD_POLL_SLEEP_US,
- MCP251XFD_POLL_TIMEOUT_US);
+ max(MCP251XFD_POLL_TIMEOUT_US,
+ (unsigned int)(CANFD_FRAME_LEN_MAX *
+ BITS_PER_BYTE *
+ CAN_BIT_STUFFING_OVERHEAD +
+ CAN_IDLE_CONDITION_SAMPLES) *
+ USEC_PER_SEC / bt->bitrate));
if (err != -ETIMEDOUT && err != -EBADMSG)
return err;
diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd.h b/drivers/net/can/spi/mcp251xfd/mcp251xfd.h
index 7024ff0cc2c0c..412d58d84fb63 100644
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd.h
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd.h
@@ -432,6 +432,15 @@ static_assert(MCP251XFD_FIFO_RX_NUM <= 4U);
/* Use Half Duplex SPI transfers */
#define MCP251XFD_QUIRK_HALF_DUPLEX BIT(5)
+/* CAN bit stuffing overhead multiplication factor */
+#define CAN_BIT_STUFFING_OVERHEAD 1.2
+
+/* Number of samples after which an idle condition is present on the bus
+ * as specified in the ISO. This is 11 consecutive sampled recessive bits
+ * after a full frame (if one is currently in transmission).
+ */
+#define CAN_IDLE_CONDITION_SAMPLES 11
+
struct mcp251xfd_hw_tef_obj {
u32 id;
u32 flags;
--
2.39.2
