On 04.05.2023 21:50:59, Marek Vasut wrote:
> From: Fedor Ross <fedor.ross@xxxxxxx>
>
> Make `MCP251XFD_POLL_TIMEOUT_US` timeout calculation dynamic. Use
> maximum of 1ms and bit time of one full 72 bytes CANFD frame at the
> current bitrate.
The 1ms was arbitrary chosen by me during development. The previous
driver by Martin Sperl uses a hardcoded loop of 256 retries and no
explicit sleep.
The datasheet "MCP25xxFD Family Reference Manual" says it needs an idle
bus.
> 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: 55e5b97f003e8 ("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
> ---
> drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c | 4 +++-
> 1 file changed, 3 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..9908843798cef 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 +252,8 @@ __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,
> + 576 * USEC_PER_SEC / bt->bitrate));
Let's use CANFD_FRAME_LEN_MAX * BITS_PER_BYTE instead of 576. I can fix
this while applying.
> if (err != -ETIMEDOUT && err != -EBADMSG)
> return err;
>
> --
> 2.39.2
>
>
Marc
--
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