[PATCH net-next v3] candev: allow SJW user setting for bittiming calculation
From: Oliver Hartkopp <hidden>
Date: 2011-09-28 12:50:11
This patch adds support for SJW user settings to not set the synchronization
jump width (SJW) to 1 in any case when using the in-kernel bittiming
calculation.
The ip-tool from iproute2 already supports to pass the user defined SJW
value. The given SJW value is sanitized with the controller specific sjw_max
and the calculated tseg2 value. As the SJW can have values up to 4 providing
this value will lead to the maximum possible SJW automatically. A higher SJW
allows higher controller oscillator tolerances.
Signed-off-by: Oliver Hartkopp <redacted>
Acked-by: Wolfgang Grandegger <redacted>
---
v2: Resend due to wrong mail address header encoding.
v3: - Detected malformed patch format due to line break in function name
- Added Acked-by: from Wolfgang Grandegger
diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index 9bf1116..25695bd 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c@@ -150,7 +150,19 @@ static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt) bt->prop_seg = tseg1 / 2; bt->phase_seg1 = tseg1 - bt->prop_seg; bt->phase_seg2 = tseg2; - bt->sjw = 1; + + /* check for sjw user settings */ + if (!bt->sjw || !btc->sjw_max) + bt->sjw = 1; + else { + /* bt->sjw is at least 1 -> sanitize upper bound to sjw_max */ + if (bt->sjw > btc->sjw_max) + bt->sjw = btc->sjw_max; + /* bt->sjw must not be higher than tseg2 */ + if (tseg2 < bt->sjw) + bt->sjw = tseg2; + } + bt->brp = best_brp; /* real bit-rate */ bt->bitrate = priv->clock.freq / (bt->brp * (tseg1 + tseg2 + 1));