Re: [PATCH net-next v9 08/10] net: ethernet: ti: am65-cpsw: add mqprio qdisc offload in channel mode

[Roger Quadros <rogerq@kernel.org>]

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@ti.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@ti.com>
>> Signed-off-by: Roger Quadros <rogerq@kernel.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