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authorOliver Hartkopp <socketcan@hartkopp.net>2011-09-28 02:50:11 +0000
committerDavid S. Miller <davem@davemloft.net>2011-09-28 13:41:51 -0400
commit2e1143742789463c00ed5e7f9bf471f2b707b493 (patch)
treee0b3aa72bccbbf8aa5e5236a5c310c6ee4eaeef3 /drivers/net/can/dev.c
parentd4fa0e35fdbd54acf791fa3793d6d17f7795f7ae (diff)
downloadop-kernel-dev-2e1143742789463c00ed5e7f9bf471f2b707b493.zip
op-kernel-dev-2e1143742789463c00ed5e7f9bf471f2b707b493.tar.gz
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.c14
1 files changed, 13 insertions, 1 deletions
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));
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