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Message-ID: <239a5cbc-126f-4c27-bbbc-2b8b102716d5@kernel.org>
Date: Mon, 18 Dec 2023 17:34:26 +0200
From: Roger Quadros <rogerq@...nel.org>
To: Simon Horman <horms@...nel.org>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
pabeni@...hat.com, shuah@...nel.org, vladimir.oltean@....com,
s-vadapalli@...com, r-gunasekaran@...com, vigneshr@...com, srk@...com,
p-varis@...com, netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-kselftest@...r.kernel.org
Subject: Re: [PATCH net-next v9 08/10] net: ethernet: ti: am65-cpsw: add
mqprio qdisc offload in channel mode
Hi Simon,
On 18/12/2023 15:43, Simon Horman wrote:
> On Fri, Dec 15, 2023 at 03:20:46PM +0200, Roger Quadros wrote:
>> From: Grygorii Strashko <grygorii.strashko@...com>
>>
>> This patch adds MQPRIO Qdisc offload in full 'channel' mode which allows
>> not only setting up pri:tc mapping, but also configuring TX shapers
>> (rate-limiting) on external port FIFOs.
>>
>> The MQPRIO Qdisc offload is expected to work with or without VLAN/priority
>> tagged packets.
>>
>> The CPSW external Port FIFO has 8 Priority queues. The rate-limit can be
>> set for each of these priority queues. Which Priority queue a packet is
>> assigned to depends on PN_REG_TX_PRI_MAP register which maps header
>> priority to switch priority.
>>
>> The header priority of a packet is assigned via the RX_PRI_MAP_REG which
>> maps packet priority to header priority.
>>
>> The packet priority is either the VLAN priority (for VLAN tagged packets)
>> or the thread/channel offset.
>>
>> For simplicity, we assign the same priority queue to all queues of a
>> Traffic Class so it can be rate-limited correctly.
>>
>> Configuration example:
>> ethtool -L eth1 tx 5
>> ethtool --set-priv-flags eth1 p0-rx-ptype-rrobin off
>>
>> tc qdisc add dev eth1 parent root handle 100: mqprio num_tc 3 \
>> map 0 0 1 2 0 0 0 0 0 0 0 0 0 0 0 0 \
>> queues 1@0 1@1 1@2 hw 1 mode channel \
>> shaper bw_rlimit min_rate 0 100mbit 200mbit max_rate 0 101mbit 202mbit
>>
>> tc qdisc replace dev eth2 handle 100: parent root mqprio num_tc 1 \
>> map 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 queues 1@0 hw 1
>>
>> ip link add link eth1 name eth1.100 type vlan id 100
>> ip link set eth1.100 type vlan egress 0:0 1:1 2:2 3:3 4:4 5:5 6:6 7:7
>>
>> In the above example two ports share the same TX CPPI queue 0 for low
>> priority traffic. 3 traffic classes are defined for eth1 and mapped to:
>> TC0 - low priority, TX CPPI queue 0 -> ext Port 1 fifo0, no rate limit
>> TC1 - prio 2, TX CPPI queue 1 -> ext Port 1 fifo1, CIR=100Mbit/s, EIR=1Mbit/s
>> TC2 - prio 3, TX CPPI queue 2 -> ext Port 1 fifo2, CIR=200Mbit/s, EIR=2Mbit/s
>>
>> Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
>> Signed-off-by: Roger Quadros <rogerq@...nel.org>
>
> ...
>
>> diff --git a/drivers/net/ethernet/ti/am65-cpsw-qos.c b/drivers/net/ethernet/ti/am65-cpsw-qos.c
>> index 9f0a05e763d1..7ad7af3b3c60 100644
>> --- a/drivers/net/ethernet/ti/am65-cpsw-qos.c
>> +++ b/drivers/net/ethernet/ti/am65-cpsw-qos.c
>> @@ -7,6 +7,7 @@
>> */
>>
>> #include <linux/pm_runtime.h>
>> +#include <linux/math.h>
>> #include <linux/time.h>
>> #include <net/pkt_cls.h>
>>
>> @@ -15,6 +16,8 @@
>> #include "am65-cpts.h"
>> #include "cpsw_ale.h"
>>
>> +#define TO_MBPS(x) DIV_ROUND_UP((x), BYTES_PER_MBIT)
>
> Hi Grygorii and Roger,
>
> a minor nit from my side: in order for BYTES_PER_MBIT to be defined
> linux/units.h needs to be included. But that isn't added until
> the next patch.
Thanks for the catch. I'll fix it in next spin.
--
cheers,
-roger
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