Re: [PATCH v2 1/6] ethdev: support setting lanes

[Damodharam Ammepalli <damodharam.ammepalli@broadcom.com>]

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On Mon, Apr 1, 2024 at 1:07 PM Thomas Monjalon <thomas@monjalon.net> wrote:
>
> 30/03/2024 12:38, huangdengdui:
> > But, there are different solutions for the device to report the setting
> > lane capability, as following:
> > 1. Like the current patch, reporting device capabilities in speed and
> >    lane coupling mode. However, if we use this solution, we will have
> >    to couple the the lanes setting with speed setting.
> >
> > 2. Like the Damodharam's RFC patch [1], the device reports the maximum
> >    number of supported lanes. Users can config a lane randomly,
> >    which is completely separated from the speed.
> >
> > 3. Similar to the FEC capability reported by a device, the device reports the
> >    relationship table of the number of lanes supported by the speed,
> >    for example:
> >       speed    lanes_capa
> >       50G      1,2
> >       100G     1,2,4
> >       200G     2,4
> >
> > Options 1 and 2 have been discussed a lot above.
> >
> > For solution 1, the speed and lanes are over-coupled, and the implementation is too
> > complex. But I think it's easier to understand and easier for the device to report
> > capabilities. In addition, the ethtool reporting capability also uses this mode.
> >
> > For solution 2, as huisong said that user don't know what lanes should or can be set
> > for a specified speed on one NIC.
> >
> > I think that when the device reports the capability, the lanes should be associated
> > with the speed. In this way, users can know which lanes are supported by the current
> > speed and verify the configuration validity.
> >
> > So I think solution 3 is better. What do you think?
>
> I don't understand your proposals.
> Please could you show the function signature for each option?
>
>
>
testpmd can query the driver, and driver can export latest bit-map say in,
rte_eth_speed_lanes_get()->supported_bmap

0  1Gb   link speed
1  10Gb  (NRZ: 10G per lane, 1 lane) link speed
2  25Gb  (NRZ: 25G per lane, 1 lane) link speed
3  40Gb  (NRZ: 10G per lane, 4 lanes) link speed
4  50Gb  (NRZ: 25G per lane, 2 lanes) link speed
5  100Gb (NRZ: 25G per lane, 4 lanes) link speed
6  50Gb  (PAM4-56: 50G per lane, 1 lane) link speed
7  100Gb (PAM4-56: 50G per lane, 2 lanes) link speed
8  200Gb (PAM4-56: 50G per lane, 4 lanes) link speed
9  400Gb (PAM4-56: 50G per lane, 8 lanes) link speed
10 100Gb (PAM4-112: 100G per lane, 1 lane) link speed
11 200Gb (PAM4-112: 100G per lane, 2 lanes) link speed
12 400Gb (PAM4-112: 100G per lane, 4 lanes) link speed
13 800Gb (PAM4-112: 100G per lane, 8 lanes) link speed
14 For future

In cmd_config_speed_specific_parsed()
   if (parse_and_check_speed_duplex(res->value1, res->value2, &link_speed) < 0)
        return;
+ /* validate speed x lanes combo */
+ if (!cmd_validate_lanes(res->id, link_speed))
+ return;

Driver can validate the rest of other internal link parameters in
rte_eth_dev_start() before
applying the config to the hardware.

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