RE: [PATCH v3] netpoll: Remove 4s sleep during carrier detection

[David Laight]

From: Breno Leitao
> Sent: 25 January 2023 18:53
> This patch removes the msleep(4s) during netpoll_setup() if the carrier
> appears instantly.
> 
> Here are some scenarios where this workaround is counter-productive in
> modern ages:
> 
> Servers which have BMC communicating over NC-SI via the same NIC as gets
> used for netconsole. BMC will keep the PHY up, hence the carrier
> appearing instantly.
> 
> The link is fibre, SERDES getting sync could happen within 0.1Hz, and
> the carrier also appears instantly.
> 
> Other than that, if a driver is reporting instant carrier and then
> losing it, this is probably a driver bug.

I can't help feeling that this will break something.
The 4 second delay does look counter productive though.
Obvious alternatives are 'wait a bit before the first check'
and 'require carrier to be present for a few checks'.

It also has to be said that checking every ms seems over enthusiastic.

	David

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