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authorVladimir Oltean <vladimir.oltean@nxp.com>2022-09-05 20:01:24 +0300
committerDavid S. Miller <davem@davemloft.net>2022-09-07 15:44:04 +0300
commit843794bbdef83955ae5b43dfafc355c3786e2145 (patch)
treee58180ba1c5162485048bab59cda6b0f84c4c6ad
parent11afdc6526de0e0368c05da632a8c0d29fc60bb8 (diff)
downloadlinux-843794bbdef83955ae5b43dfafc355c3786e2145.tar.xz
net: dsa: felix: disable cut-through forwarding for frames oversized for tc-taprio
Experimentally, it looks like when QSYS_QMAXSDU_CFG_7 is set to 605, frames even way larger than 601 octets are transmitted even though these should be considered as oversized, according to the documentation, and dropped. Since oversized frame dropping depends on frame size, which is only known at the EOF stage, and therefore not at SOF when cut-through forwarding begins, it means that the switch cannot take QSYS_QMAXSDU_CFG_* into consideration for traffic classes that are cut-through. Since cut-through forwarding has no UAPI to control it, and the driver enables it based on the mantra "if we can, then why not", the strategy is to alter vsc9959_cut_through_fwd() to take into consideration which tc's have oversize frame dropping enabled, and disable cut-through for them. Then, from vsc9959_tas_guard_bands_update(), we re-trigger the cut-through determination process. There are 2 strategies for vsc9959_cut_through_fwd() to determine whether a tc has oversized dropping enabled or not. One is to keep a bit mask of traffic classes per port, and the other is to read back from the hardware registers (a non-zero value of QSYS_QMAXSDU_CFG_* means the feature is enabled). We choose reading back from registers, because struct ocelot_port is shared with drivers (ocelot, seville) that don't support either cut-through nor tc-taprio, and we don't have a felix specific extension of struct ocelot_port. Furthermore, reading registers from the Felix hardware is quite cheap, since they are memory-mapped. Fixes: 55a515b1f5a9 ("net: dsa: felix: drop oversized frames with tc-taprio instead of hanging the port") Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--drivers/net/dsa/ocelot/felix_vsc9959.c122
1 files changed, 79 insertions, 43 deletions
diff --git a/drivers/net/dsa/ocelot/felix_vsc9959.c b/drivers/net/dsa/ocelot/felix_vsc9959.c
index 262be2cf4e4b..ad7c795d6612 100644
--- a/drivers/net/dsa/ocelot/felix_vsc9959.c
+++ b/drivers/net/dsa/ocelot/felix_vsc9959.c
@@ -1557,6 +1557,65 @@ static void vsc9959_tas_min_gate_lengths(struct tc_taprio_qopt_offload *taprio,
min_gate_len[tc] = 0;
}
+/* ocelot_write_rix is a macro that concatenates QSYS_MAXSDU_CFG_* with _RSZ,
+ * so we need to spell out the register access to each traffic class in helper
+ * functions, to simplify callers
+ */
+static void vsc9959_port_qmaxsdu_set(struct ocelot *ocelot, int port, int tc,
+ u32 max_sdu)
+{
+ switch (tc) {
+ case 0:
+ ocelot_write_rix(ocelot, max_sdu, QSYS_QMAXSDU_CFG_0,
+ port);
+ break;
+ case 1:
+ ocelot_write_rix(ocelot, max_sdu, QSYS_QMAXSDU_CFG_1,
+ port);
+ break;
+ case 2:
+ ocelot_write_rix(ocelot, max_sdu, QSYS_QMAXSDU_CFG_2,
+ port);
+ break;
+ case 3:
+ ocelot_write_rix(ocelot, max_sdu, QSYS_QMAXSDU_CFG_3,
+ port);
+ break;
+ case 4:
+ ocelot_write_rix(ocelot, max_sdu, QSYS_QMAXSDU_CFG_4,
+ port);
+ break;
+ case 5:
+ ocelot_write_rix(ocelot, max_sdu, QSYS_QMAXSDU_CFG_5,
+ port);
+ break;
+ case 6:
+ ocelot_write_rix(ocelot, max_sdu, QSYS_QMAXSDU_CFG_6,
+ port);
+ break;
+ case 7:
+ ocelot_write_rix(ocelot, max_sdu, QSYS_QMAXSDU_CFG_7,
+ port);
+ break;
+ }
+}
+
+static u32 vsc9959_port_qmaxsdu_get(struct ocelot *ocelot, int port, int tc)
+{
+ switch (tc) {
+ case 0: return ocelot_read_rix(ocelot, QSYS_QMAXSDU_CFG_0, port);
+ case 1: return ocelot_read_rix(ocelot, QSYS_QMAXSDU_CFG_1, port);
+ case 2: return ocelot_read_rix(ocelot, QSYS_QMAXSDU_CFG_2, port);
+ case 3: return ocelot_read_rix(ocelot, QSYS_QMAXSDU_CFG_3, port);
+ case 4: return ocelot_read_rix(ocelot, QSYS_QMAXSDU_CFG_4, port);
+ case 5: return ocelot_read_rix(ocelot, QSYS_QMAXSDU_CFG_5, port);
+ case 6: return ocelot_read_rix(ocelot, QSYS_QMAXSDU_CFG_6, port);
+ case 7: return ocelot_read_rix(ocelot, QSYS_QMAXSDU_CFG_7, port);
+ default:
+ return 0;
+ }
+}
+
/* Update QSYS_PORT_MAX_SDU to make sure the static guard bands added by the
* switch (see the ALWAYS_GUARD_BAND_SCH_Q comment) are correct at all MTU
* values (the default value is 1518). Also, for traffic class windows smaller
@@ -1613,6 +1672,8 @@ static void vsc9959_tas_guard_bands_update(struct ocelot *ocelot, int port)
vsc9959_tas_min_gate_lengths(ocelot_port->taprio, min_gate_len);
+ mutex_lock(&ocelot->fwd_domain_lock);
+
for (tc = 0; tc < OCELOT_NUM_TC; tc++) {
u64 remaining_gate_len_ps;
u32 max_sdu;
@@ -1664,47 +1725,14 @@ static void vsc9959_tas_guard_bands_update(struct ocelot *ocelot, int port)
max_sdu);
}
- /* ocelot_write_rix is a macro that concatenates
- * QSYS_MAXSDU_CFG_* with _RSZ, so we need to spell out
- * the writes to each traffic class
- */
- switch (tc) {
- case 0:
- ocelot_write_rix(ocelot, max_sdu, QSYS_QMAXSDU_CFG_0,
- port);
- break;
- case 1:
- ocelot_write_rix(ocelot, max_sdu, QSYS_QMAXSDU_CFG_1,
- port);
- break;
- case 2:
- ocelot_write_rix(ocelot, max_sdu, QSYS_QMAXSDU_CFG_2,
- port);
- break;
- case 3:
- ocelot_write_rix(ocelot, max_sdu, QSYS_QMAXSDU_CFG_3,
- port);
- break;
- case 4:
- ocelot_write_rix(ocelot, max_sdu, QSYS_QMAXSDU_CFG_4,
- port);
- break;
- case 5:
- ocelot_write_rix(ocelot, max_sdu, QSYS_QMAXSDU_CFG_5,
- port);
- break;
- case 6:
- ocelot_write_rix(ocelot, max_sdu, QSYS_QMAXSDU_CFG_6,
- port);
- break;
- case 7:
- ocelot_write_rix(ocelot, max_sdu, QSYS_QMAXSDU_CFG_7,
- port);
- break;
- }
+ vsc9959_port_qmaxsdu_set(ocelot, port, tc, max_sdu);
}
ocelot_write_rix(ocelot, maxlen, QSYS_PORT_MAX_SDU, port);
+
+ ocelot->ops->cut_through_fwd(ocelot);
+
+ mutex_unlock(&ocelot->fwd_domain_lock);
}
static void vsc9959_sched_speed_set(struct ocelot *ocelot, int port,
@@ -2797,7 +2825,7 @@ static void vsc9959_cut_through_fwd(struct ocelot *ocelot)
{
struct felix *felix = ocelot_to_felix(ocelot);
struct dsa_switch *ds = felix->ds;
- int port, other_port;
+ int tc, port, other_port;
lockdep_assert_held(&ocelot->fwd_domain_lock);
@@ -2841,19 +2869,27 @@ static void vsc9959_cut_through_fwd(struct ocelot *ocelot)
min_speed = other_ocelot_port->speed;
}
- /* Enable cut-through forwarding for all traffic classes. */
- if (ocelot_port->speed == min_speed)
+ /* Enable cut-through forwarding for all traffic classes that
+ * don't have oversized dropping enabled, since this check is
+ * bypassed in cut-through mode.
+ */
+ if (ocelot_port->speed == min_speed) {
val = GENMASK(7, 0);
+ for (tc = 0; tc < OCELOT_NUM_TC; tc++)
+ if (vsc9959_port_qmaxsdu_get(ocelot, port, tc))
+ val &= ~BIT(tc);
+ }
+
set:
tmp = ocelot_read_rix(ocelot, ANA_CUT_THRU_CFG, port);
if (tmp == val)
continue;
dev_dbg(ocelot->dev,
- "port %d fwd mask 0x%lx speed %d min_speed %d, %s cut-through forwarding\n",
+ "port %d fwd mask 0x%lx speed %d min_speed %d, %s cut-through forwarding on TC mask 0x%x\n",
port, mask, ocelot_port->speed, min_speed,
- val ? "enabling" : "disabling");
+ val ? "enabling" : "disabling", val);
ocelot_write_rix(ocelot, val, ANA_CUT_THRU_CFG, port);
}