Merge patch series "can: bittiming: cleanups and rework SJW handling"

Marc Kleine-Budde <[email protected]> says:

several people noticed that on modern CAN controllers with wide bit
timing registers the default SJW of 1 can result in unstable or no
synchronization to the CAN network. See Patch 14/17 for details.

During review of v1 Vincent pointed out that the original code and the
series doesn't always check user provided bit timing parameters,
sometimes silently limits them and the return error values are not
consistent.

This series first cleans up some code in bittiming.c, replacing
open-coded variants by macros or functions (Patches 1, 2).

Patch 3 adds the missing assignment of the effective TQ if the
interface is configured with low level timing parameters.

Patch 4 is another code cleanup.

Patches 5, 6 check the bit timing parameter during interface
registration.

Patch 7 adds a validation of the sample point.

The patches 8-13 convert the error messages from netdev_err() to
NL_SET_ERR_MSG_FMT, factor out the SJW handling from
can_fixup_bittiming(), add checking and error messages for the
individual limits and harmonize the error return values.

Patch 14 changes the default SJW value from 1 to min(Phase Seg1, Phase
Seg2 / 2).

Patch 15 switches can_calc_bittiming() to use the new SJW handling.

Patch 16 converts can_calc_bittiming() to NL_SET_ERR_MSG_FMT().

And patch 16 adds a NL_SET_ERR_MSG_FMT() error message to
can_validate_bitrate().

v1: https://lore.kernel.org/all/[email protected]

Link: https://lore.kernel.org/all/[email protected]
Signed-off-by: Marc Kleine-Budde <[email protected]>

1 files changed, 8 insertions, 2 deletions

diff --git a/include/linux/can/bittiming.h b/include/linux/can/bittiming.h
index ef0a77173e3c..6cb2ae308e3f 100644
--- a/include/linux/can/bittiming.h
+++ b/include/linux/can/bittiming.h
@@ -116,7 +116,7 @@ struct can_tdc_const {
 
 #ifdef CONFIG_CAN_CALC_BITTIMING
 int can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt,
-		       const struct can_bittiming_const *btc);
+		       const struct can_bittiming_const *btc, struct netlink_ext_ack *extack);
 
 void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,
 		   const struct can_bittiming *dbt,
@@ -138,10 +138,16 @@ can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,
 }
 #endif /* CONFIG_CAN_CALC_BITTIMING */
 
+void can_sjw_set_default(struct can_bittiming *bt);
+
+int can_sjw_check(const struct net_device *dev, const struct can_bittiming *bt,
+		  const struct can_bittiming_const *btc, struct netlink_ext_ack *extack);
+
 int can_get_bittiming(const struct net_device *dev, struct can_bittiming *bt,
 		      const struct can_bittiming_const *btc,
 		      const u32 *bitrate_const,
-		      const unsigned int bitrate_const_cnt);
+		      const unsigned int bitrate_const_cnt,
+		      struct netlink_ext_ack *extack);
 
 /*
  * can_bit_time() - Duration of one bit