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authorVladimir Oltean <vladimir.oltean@nxp.com>2021-01-15 05:11:19 +0300
committerJakub Kicinski <kuba@kernel.org>2021-01-16 07:02:34 +0300
commita4ae997adcbdf8ead133bafa5e9e2d6925c576b6 (patch)
treec81c721a94f7f626f0fa680e7af6f56ab4b1fc8b /drivers/net/ethernet/mscc/Makefile
parent6c30384eb1dec96b678ff9c01c15134b1a0e81f4 (diff)
downloadlinux-a4ae997adcbdf8ead133bafa5e9e2d6925c576b6.tar.xz
net: mscc: ocelot: initialize watermarks to sane defaults
This is meant to be a gentle introduction into the world of watermarks on ocelot. The code is placed in ocelot_devlink.c because it will be integrated with devlink, even if it isn't right now. My first step was intended to be to replicate the default configuration of the congestion watermarks programatically, since they are now going to be tuned by the user. But after studying and understanding through trial and error how they work, I now believe that the configuration used out of reset does not do justice to the word "reservation", since the sum of all reservations exceeds the total amount of resources (otherwise said, all reservations cannot be fulfilled at the same time, which means that, contrary to the reference manual, they don't guarantee anything). As an example, here's a dump of the reservation watermarks for frame buffers, for port 0 (for brevity, the ports 1-6 were omitted, but they have the same configuration): BUF_Q_RSRV_I(port 0, prio 0) = max 3000 bytes BUF_Q_RSRV_I(port 0, prio 1) = max 3000 bytes BUF_Q_RSRV_I(port 0, prio 2) = max 3000 bytes BUF_Q_RSRV_I(port 0, prio 3) = max 3000 bytes BUF_Q_RSRV_I(port 0, prio 4) = max 3000 bytes BUF_Q_RSRV_I(port 0, prio 5) = max 3000 bytes BUF_Q_RSRV_I(port 0, prio 6) = max 3000 bytes BUF_Q_RSRV_I(port 0, prio 7) = max 3000 bytes Otherwise said, every port-tc has an ingress reservation of 3000 bytes, and there are 7 ports in VSC9959 Felix (6 user ports and 1 CPU port). Concentrating only on the ingress reservations, there are, in total, 8 [traffic classes] x 7 [ports] x 3000 [bytes] = 168,000 bytes of memory reserved on ingress. But, surprise, Felix only has 128 KB of packet buffer in total... A similar thing happens with Seville, which has a larger packet buffer, but also more ports, and the default configuration is also overcommitted. This patch disables the (apparently) bogus reservations and moves all resources to the shared area. This way, real reservations can be set up by the user, using devlink-sb. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'drivers/net/ethernet/mscc/Makefile')
-rw-r--r--drivers/net/ethernet/mscc/Makefile3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/net/ethernet/mscc/Makefile b/drivers/net/ethernet/mscc/Makefile
index 58f94c3d80f9..346bba2730ad 100644
--- a/drivers/net/ethernet/mscc/Makefile
+++ b/drivers/net/ethernet/mscc/Makefile
@@ -6,7 +6,8 @@ mscc_ocelot_switch_lib-y := \
ocelot_police.o \
ocelot_vcap.o \
ocelot_flower.o \
- ocelot_ptp.o
+ ocelot_ptp.o \
+ ocelot_devlink.o
obj-$(CONFIG_MSCC_OCELOT_SWITCH) += mscc_ocelot.o
mscc_ocelot-y := \
ocelot_vsc7514.o \