diff options
| author | Oliver Hartkopp <socketcan@hartkopp.net> | 2011-09-28 02:50:11 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2011-09-28 13:41:51 -0400 |
| commit | 2e1143742789463c00ed5e7f9bf471f2b707b493 (patch) | |
| tree | e0b3aa72bccbbf8aa5e5236a5c310c6ee4eaeef3 /drivers/net/can/dev.c | |
| parent | d4fa0e35fdbd54acf791fa3793d6d17f7795f7ae (diff) | |
| download | lwn-2e1143742789463c00ed5e7f9bf471f2b707b493.tar.gz lwn-2e1143742789463c00ed5e7f9bf471f2b707b493.zip | |
candev: allow SJW user setting for bittiming calculation
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 <socketcan@hartkopp.net>
Acked-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/can/dev.c')
| -rw-r--r-- | drivers/net/can/dev.c | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c index 9bf1116e5b5e..25695bde0549 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)); |