linux-kernel - Re: [PATCH] IB/mlx5: give back valid speed/width even without plugged in SFP module

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Date:   Sat, 28 Oct 2017 12:42:44 +0200
From:   Thomas Bogendoerfer <tbogendoerfer@...e.de>
To:     Hal Rosenstock <hal@....mellanox.co.il>
Cc:     Ghazale Hosseinabadi <ghazale.hosseinabadi@...cle.com>,
        linux-rdma@...r.kernel.org, matanb@...lanox.com,
        leonro@...lanox.com, parav@...lanox.com,
        linux-kernel@...r.kernel.org, dledford@...hat.com
Subject: Re: [PATCH] IB/mlx5: give back valid speed/width even without
 plugged in SFP module

On Fri, 27 Oct 2017 19:19:05 -0400
Hal Rosenstock <hal@....mellanox.co.il> wrote:

> On 10/27/2017 7:04 PM, Ghazale Hosseinabadi wrote:
> > 
> > 
> > On 10/27/2017 03:52 PM, Hal Rosenstock wrote:
> >> On 10/27/2017 5:54 PM, Ghazale Hosseinabadi wrote:
> >>> When running ibstat (if transceiver is not connected in adapter):
> >>>
> >>> ibpanic: [7851] main: stat of IB device 'mlx5_1' failed: Invalid
> >>> argument
> >> Any output before that ?
> > no, It only prints this line.

rate_show() generates an EINVAL, that's propably what ibstat/*libs confuses.

> and setting the width to 1x in the driver so the rate file is properly
> populated fixes this ? 

yes, because then rate_show() will not return EINVAL.

> I must be missing something as to what is going on in this scenario.
> 
> sysfs.c:rate_show is inconsistent as it paves over an invalid speed
> setting that to SDR but does not pave over invalid width returning
> -EINVAL but this comment is in another "direction".

I thought about going in the other direction by making the speed/width unknown case
somehow visible in rate_show(). When I checked all other drivers only mlx5 stand out
so I decided to only change mlx5. But I make a change to let rate_show() print out, 
that is currently has no rate for the port.

Thomas.

-- 
Thomas Bogendoerfer <tbogendoerfer@...e.de>