netdev - Re: [PATCH 12/15] habanalabs/gaudi: add debugfs entries for the NIC

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Message-ID: <20200910131629.65b3e02c@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Thu, 10 Sep 2020 13:16:29 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Oded Gabbay <oded.gabbay@...il.com>
Cc:     "Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>,
        netdev@...r.kernel.org, SW_Drivers <SW_Drivers@...ana.ai>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "David S. Miller" <davem@...emloft.net>,
        Omer Shpigelman <oshpigelman@...ana.ai>
Subject: Re: [PATCH 12/15] habanalabs/gaudi: add debugfs entries for the NIC

On Thu, 10 Sep 2020 23:10:47 +0300 Oded Gabbay wrote:
> On Thu, Sep 10, 2020 at 11:01 PM Jakub Kicinski <kuba@...nel.org> wrote:
> >
> > On Thu, 10 Sep 2020 19:11:23 +0300 Oded Gabbay wrote:  
> > > From: Omer Shpigelman <oshpigelman@...ana.ai>
> > >
> > > Add several debugfs entries to help us debug the NIC engines and ports and
> > > also the communication layer of the DL training application that use them.
> > >
> > > There are eight new entries. Detailed description is in the documentation
> > > file but here is a summary:
> > >
> > > - nic_mac_loopback: enable mac loopback mode per port
> > > - nic_ports_status: print physical connection status per port
> > > - nic_pcs_fail_time_frame: configure windows size for measuring pcs
> > >                            failures
> > > - nic_pcs_fail_threshold: configure pcs failures threshold for
> > >                           reconfiguring the link
> > > - nic_pam4_tx_taps: configure PAM4 TX taps
> > > - nic_polarity: configure polarity for NIC port lanes
> > > - nic_check_link: configure whether to check the PCS link periodically
> > > - nic_phy_auto_neg_lpbk: enable PHY auto-negotiation loopback
> > >
> > > Signed-off-by: Omer Shpigelman <oshpigelman@...ana.ai>
> > > Reviewed-by: Oded Gabbay <oded.gabbay@...il.com>
> > > Signed-off-by: Oded Gabbay <oded.gabbay@...il.com>  
> >
> > debugfs configuration interfaces are not acceptable in netdev.  
> 
> no problem, but can we have only these two entries:
> > - nic_mac_loopback: enable mac loopback mode per port
> > - nic_ports_status: print physical connection status per port  
> 
> nic_ports_status is print only (not configuration).

Doesn't seem like this one shows any more information than can be
queried with ethtool, right?

> nic_mac_loopback
> is to set a port to loopback mode and out of it. It's not really
> configuration but rather a mode change.

What is this loopback for? Testing?