linux-imx

can: flexcan: implement error passive state quirk

Add FLEXCAN_QUIRK_BROKEN_PERR_STATE for better description of the
missing error passive interrupt quirk.

Error interrupt flooding may happen if the broken error state quirk fix
is enabled. For example, in case there is singled out node on the bus
and the node sends a frame, then error interrupt flooding happens and
will not stop because the node cannot go to bus off. The flooding will
stop after another node connected to the bus again.

If high bitrate configured on the low end system, then the flooding
may causes performance issue, hence, this patch mitigates this by:
1. disable error interrupt upon error passive state transition
2. re-enable error interrupt upon error warning state transition
3. disable/enable error interrupt upon error active state transition
   depends on FLEXCAN_QUIRK_BROKEN_WERR_STATE

In this way, the driver is still able to report correct state
transitions without additional latency. When there are bus problems,
flooding of error interrupts is limited to the number of frames required
to change state from error warning to error passive if the core has
[TR]WRN_INT connected (FLEXCAN_QUIRK_BROKEN_WERR_STATE is not enabled),
otherwise, the flooding is limited to the number of frames required to
change state from error active to error passive.

Signed-off-by: Zhu Yi <yi.zhu5@cn.bosch.com>
Signed-off-by: Mark Jonas <mark.jonas@de.bosch.com>
Acked-by: Wolfgang Grandegger <wg@grandegger.com>
Cc: linux-stable <stable@vger.kernel.org> # >= v4.11
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>