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net: mscc: ocelot: divide watermark value by 60 when writing to SYS_ATOP 

Tail dropping is enabled for a port when:

1. A source port consumes more packet buffers than the watermark encoded
   in SYS:PORT:ATOP_CFG.ATOP.

AND

2. Total memory use exceeds the consumption watermark encoded in
   SYS:PAUSE_CFG:ATOP_TOT_CFG.

The unit of these watermarks is a 60 byte memory cell. That unit is
programmed properly into ATOP_TOT_CFG, but not into ATOP. Actually when
written into ATOP, it would get truncated and wrap around.

Fixes: a556c76adc ("net: mscc: Add initial Ocelot switch support")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Vladimir Oltean 2020-10-05 12:09:11 +03:00 committed by David S. Miller
parent 082bb94fe1
commit 601e984f23
1 changed files with 6 additions and 6 deletions
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12
drivers/net/ethernet/mscc/ocelot.c
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@ -1253,7 +1253,7 @@ void ocelot_port_set_maxlen(struct ocelot *ocelot, int port, size_t sdu)
struct ocelot_port *ocelot_port = ocelot->ports[port];
int maxlen = sdu + ETH_HLEN + ETH_FCS_LEN;
int pause_start, pause_stop;
int atop_wm;
int atop, atop_tot;
if (port == ocelot->npi) {
maxlen += OCELOT_TAG_LEN;
@ -1274,12 +1274,12 @@ void ocelot_port_set_maxlen(struct ocelot *ocelot, int port, size_t sdu)
ocelot_fields_write(ocelot, port, SYS_PAUSE_CFG_PAUSE_STOP,
pause_stop);
/* Tail dropping watermark */
atop_wm = (ocelot->shared_queue_sz - 9 * maxlen) /
/* Tail dropping watermarks */
atop_tot = (ocelot->shared_queue_sz - 9 * maxlen) /
OCELOT_BUFFER_CELL_SZ;
ocelot_write_rix(ocelot, ocelot->ops->wm_enc(9 * maxlen),
SYS_ATOP, port);
ocelot_write(ocelot, ocelot->ops->wm_enc(atop_wm), SYS_ATOP_TOT_CFG);
atop = (9 * maxlen) / OCELOT_BUFFER_CELL_SZ;
ocelot_write_rix(ocelot, ocelot->ops->wm_enc(atop), SYS_ATOP, port);
ocelot_write(ocelot, ocelot->ops->wm_enc(atop_tot), SYS_ATOP_TOT_CFG);
}
EXPORT_SYMBOL(ocelot_port_set_maxlen);