netdev - Re: [PATCH] net: sfp: workaround GPIO input signals bounce

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Message-ID: <YyA1sfZRuoka8yhl@shell.armlinux.org.uk>
Date:   Tue, 13 Sep 2022 08:48:01 +0100
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Baruch Siach <baruch@...s.co.il>
Cc:     netdev@...r.kernel.org, Andrew Lunn <andrew@...n.ch>,
        Baruch Siach <baruch.siach@...lu.com>
Subject: Re: [PATCH] net: sfp: workaround GPIO input signals bounce

On Tue, Sep 13, 2022 at 10:43:38AM +0300, Baruch Siach wrote:
> From: Baruch Siach <baruch.siach@...lu.com>
> 
> Add a trivial debounce to avoid miss of state changes when there is no
> proper hardware debounce on the input signals. Otherwise a GPIO might
> randomly indicate high level when the signal is actually going down,
> and vice versa.
> 
> This fixes observed miss of link up event when LOS signal goes down on
> Armada 8040 based system with an optical SFP module.

NAK. This needs more inteligent handling. For systems where we poll,
your code introduces a 100us delay each time we poll and there has
been no change.

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