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Diffstat (limited to 'drivers/net/dsa/ocelot/felix_vsc9959.c')
-rw-r--r--drivers/net/dsa/ocelot/felix_vsc9959.c15
1 files changed, 10 insertions, 5 deletions
diff --git a/drivers/net/dsa/ocelot/felix_vsc9959.c b/drivers/net/dsa/ocelot/felix_vsc9959.c
index 2473bebe48e6..f966a253d1c7 100644
--- a/drivers/net/dsa/ocelot/felix_vsc9959.c
+++ b/drivers/net/dsa/ocelot/felix_vsc9959.c
@@ -1227,12 +1227,17 @@ static int vsc9959_qos_port_tas_set(struct ocelot *ocelot, int port,
if (taprio->num_entries > VSC9959_TAS_GCL_ENTRY_MAX)
return -ERANGE;
- /* Set port num and disable ALWAYS_GUARD_BAND_SCH_Q, which means set
- * guard band to be implemented for nonschedule queues to schedule
- * queues transition.
+ /* Enable guard band. The switch will schedule frames without taking
+ * their length into account. Thus we'll always need to enable the
+ * guard band which reserves the time of a maximum sized frame at the
+ * end of the time window.
+ *
+ * Although the ALWAYS_GUARD_BAND_SCH_Q bit is global for all ports, we
+ * need to set PORT_NUM, because subsequent writes to PARAM_CFG_REG_n
+ * operate on the port number.
*/
- ocelot_rmw(ocelot,
- QSYS_TAS_PARAM_CFG_CTRL_PORT_NUM(port),
+ ocelot_rmw(ocelot, QSYS_TAS_PARAM_CFG_CTRL_PORT_NUM(port) |
+ QSYS_TAS_PARAM_CFG_CTRL_ALWAYS_GUARD_BAND_SCH_Q,
QSYS_TAS_PARAM_CFG_CTRL_PORT_NUM_M |
QSYS_TAS_PARAM_CFG_CTRL_ALWAYS_GUARD_BAND_SCH_Q,
QSYS_TAS_PARAM_CFG_CTRL);