Re: [PATCH v5 net-next 3/4] net: ethernet: ti: am65-cpsw-qos: Add Frame Preemption MAC Merge support

[Roger Quadros]

On 05/10/2023 12:29, Vladimir Oltean wrote:
> On Wed, Sep 27, 2023 at 10:27:40AM +0300, Roger Quadros wrote:
>> Add driver support for viewing / changing the MAC Merge sublayer
>> parameters and seeing the verification state machine's current state
>> via ethtool.
>>
>> As hardware does not support interrupt notification for verification
>> events we resort to polling on link up. On link up we try a couple of
>> times for verification success and if unsuccessful then give up.
>>
>> The Frame Preemption feature is described in the Technical Reference
>> Manual [1] in section:
>> 	12.3.1.4.6.7 Intersperced Express Traffic (IET – P802.3br/D2.0)
>>
>> Due to Silicon Errata i2208 [2] we set limit min IET fragment size to 124.
>>
>> [1] AM62x TRM - https://www.ti.com/lit/ug/spruiv7a/spruiv7a.pdf
>> [2] AM62x Silicon Errata - https://www.ti.com/lit/er/sprz487c/sprz487c.pdf
>>
>> Signed-off-by: Roger Quadros <rogerq@xxxxxxxxxx>
>> ---
>>  drivers/net/ethernet/ti/am65-cpsw-ethtool.c | 150 ++++++++++++
>>  drivers/net/ethernet/ti/am65-cpsw-nuss.c    |   2 +
>>  drivers/net/ethernet/ti/am65-cpsw-nuss.h    |   5 +
>>  drivers/net/ethernet/ti/am65-cpsw-qos.c     | 240 ++++++++++++++++----
>>  drivers/net/ethernet/ti/am65-cpsw-qos.h     | 104 +++++++++
>>  5 files changed, 454 insertions(+), 47 deletions(-)
>>
>> Changelog:
>> v5:
>> - No change
>>
>> v4:
>> - Rebase and include in the same series as mqprio support.
>>
>> v3:
>> - Rebase on top of v6.6-rc1 and mqprio support [1]
>> - Support ethtool_ops :: get_mm_stats()
>> - drop unused variables cmn_ctrl and verify_cnt
>> - make am65_cpsw_iet_link_state_update() and
>>   am65_cpsw_iet_change_preemptible_tcs() static
>>
>> [1] https://lore.kernel.org/all/20230918075358.5878-1-rogerq@xxxxxxxxxx/
>>
>> v2:
>> - Use proper control bits for PMAC enable (AM65_CPSW_PN_CTL_IET_PORT_EN)
>>   and TX enable (AM65_CPSW_PN_IET_MAC_PENABLE)
>> - Common IET Enable (AM65_CPSW_CTL_IET_EN) is set if any port has
>>   AM65_CPSW_PN_CTL_IET_PORT_EN set.
>> - Fix workaround for erratum i2208. i.e. Limit rx_min_frag_size to 124
>> - Fix am65_cpsw_iet_get_verify_timeout_ms() to default to timeout for
>>   1G link if link is inactive.
>> - resize the RX FIFO based on pmac_enabled, not tx_enabled.
>>
>> Test Procedure:
>>
>> - 2 EVMs with AM65-CPSW network port connected to each other
>> - Run iet-setup-mqprio.sh on both
>>
>> #!/bin/sh
>> #iet-setup-mqprio.sh
>>
>> ifconfig eth0 down
>> ifconfig eth1 down
>> ethtool -L eth0 tx 4
>> ethtool --set-mm eth0 pmac-enabled on tx-enabled on verify-enabled on verify-time 10 tx-min-frag-size 124
>> ifconfig eth0 up
>> sleep 10
>>
>> tc qdisc add dev eth0 handle 100: root mqprio \
>> num_tc 4 \
>> map 0 1 2 3 \
>> queues 1@0 1@1 1@2 1@3 \
>> hw 1 \
>> mode dcb \
>> fp P P P E
>>
>> tc -g class show dev eth0
>> tc qdisc add dev eth0 clsact
>> tc filter add dev eth0 egress protocol ip prio 1 u32 match ip dport 5002 0xffff action skbedit priority 2
>> tc filter add dev eth0 egress protocol ip prio 1 u32 match ip dport 5003 0xffff action skbedit priority 3
>> ip addr add 192.168.3.102/24 dev eth0 
>>
>> - check that MAC merge verification has succeeded
>>
>> ethtool --show-mm eth0
>>
>>         MAC Merge layer state for eth0:
>>         pMAC enabled: on
>>         TX enabled: on
>>         TX active: on
>>         TX minimum fragment size: 124
>>         RX minimum fragment size: 124
>>         Verify enabled: on
>>         Verify time: 10
>>         Max verify time: 134
>>         Verification status: SUCCEEDED
>>
>> - On receiver EVM run 2 iperf instances
>>
>> iperf3 -s -i30 -p5002&
>> iperf3 -s -i30 -p5003&
>>
>> - On sender EVM run 2 iperf instances
>>
>> iperf3 -c 192.168.3.102 -u -b200M -l1472 -u -t5 -i30 -p5002&
>> iperf3 -c 192.168.3.102 -u -b50M -l1472 -u -t5 -i30 -p5003&
>>
>> - Check IET stats on sender. Look for MACMergeFragCountTx: increments
>>
>> ethtool -I --show-mm eth0
>> MAC Merge layer state for eth0:
>> pMAC enabled: on
>> TX enabled: on
>> TX active: on
>> TX minimum fragment size: 124
>> RX minimum fragment size: 124
>> Verify enabled: on
>> Verify time: 10
>> Max verify time: 134
>> Verification status: SUCCEEDED
>> Statistics:
>>   MACMergeFrameAssErrorCount: 0
>>   MACMergeFrameSmdErrorCount: 0
>>   MACMergeFrameAssOkCount: 0
>>   MACMergeFragCountRx: 0
>>   MACMergeFragCountTx: 57824
>>   MACMergeHoldCount: 0
>>
>> - Check IET stats on receiver. Look for MACMergeFragCountRx: and
>>   MACMergeFrameAssOkCount:
>>
>> ethtool -I --show-mm eth0
>> MAC Merge layer state for eth0:
>> pMAC enabled: on
>> TX enabled: on
>> TX active: on
>> TX minimum fragment size: 124
>> RX minimum fragment size: 124
>> Verify enabled: on
>> Verify time: 10
>> Max verify time: 134
>> Verification status: SUCCEEDED
>> Statistics:
>>   MACMergeFrameAssErrorCount: 0
>>   MACMergeFrameSmdErrorCount: 0
>>   MACMergeFrameAssOkCount: 57018
>>   MACMergeFragCountRx: 57824
>>   MACMergeFragCountTx: 0
>>   MACMergeHoldCount: 0
> 
> Nice of you to post commands, but could you also please clearly state
> whether the implementation passes tools/testing/selftests/net/forwarding/ethtool_mm.sh?

Honestly, I didn't spend much time with it. I will try to run
those tests and get back.

> 
>> +	val &= ~AM65_CPSW_PN_IET_MAC_MAC_ADDFRAGSIZE_MASK;
>> +	val |= AM65_CPSW_PN_IET_MAC_SET_ADDFRAGSIZE(add_frag_size);
>> +	writel(val, port->port_base + AM65_CPSW_PN_REG_IET_CTRL);
>> +
>> +	/* verify_timeout_count can only be set at valid link */
>> +	port->qos.iet.verify_time_ms = cfg->verify_time;
>> +
>> +	/* enable/disable pre-emption based on link status */
> 
> For the benefit of grep, I would appreciate if it was spelled
> "preemption" everywhere.

OK.

> 
>> +	am65_cpsw_iet_commit_preemptible_tcs(port);
>> +
>> +	mutex_unlock(&priv->mm_lock);
>> +
>> +	return 0;
>> +}
>> +
>>  static int am65_cpsw_port_est_enabled(struct am65_cpsw_port *port)
>>  {
>>  	return port->qos.est_oper || port->qos.est_admin;
>> @@ -602,6 +743,8 @@ static int am65_cpsw_setup_taprio(struct net_device *ndev, void *type_data)
>>  	if (port->qos.link_speed == SPEED_UNKNOWN)
>>  		return -ENOLINK;
>>  
>> +	am65_cpsw_iet_change_preemptible_tcs(port, taprio->mqprio.preemptible_tcs);
>> +
> 
> Hmm, why just look at the preemptible traffic classes and not at
> taprio's entire mqprio configuration? This bypasses the mapping between
> Linux traffic classes and switch priorities that you've established in
> am65_cpsw_setup_mqprio().
> 
> With the addition of the "mqprio" structure in tc_taprio_qopt_offload,
> my intention was to facilitate calling am65_cpsw_setup_mqprio() from
> am65_cpsw_setup_taprio().

OK. I will take a look at this. Thanks!

> 
>>  	return am65_cpsw_set_taprio(ndev, type_data);
>>  }

-- 
cheers,
-roger