Re: [PATCH net-next v3 2/5] ionic: Get "link_down_count" ext link stat from firmware

[Eric Joyner <eric.joyner@amd.com>]

On 6/9/2026 2:26 PM, Jakub Kicinski wrote:
>> Is this a big enough issue to deal with? Is link really going to go down
>> sixty-five thousand times while the driver is loaded? I guess we could have a
>> running tally, but that seems like more effort than this is worth.
> 
> Seems unlikely indeed, but drivers routinely deal with such wrapping.
> It's like 5 lines of code, no?
> 
>         u16 val = le16_to_cpu(...
> 
>         if ((u16)stats->link_down_events > val)
>                stats->link_down_events += BIT(16);
>         stats->link_down_events &= 0xffff0000;
>         stats->link_down_events |= val;
> 
> 
> This is also not great, operationally. Monitoring systems may expect
> counters to start from 0 after boot (IIUC you're saying that unless
> the card goes thru a full reset we'll keep the value from previous
> boot).
> 

Yep, that is what I've observed. I now wonder if the previous solution of having
the driver calculate this statistic may have been an attempt to bypass these
concerns.

Maybe I should go back to the original version, and have the firmware stat just
be an extra entry in "ethtool -S" for additional info?

- Eric