netdev - Re: [PATCH] net: mvpp2: add delay at the end of .mac

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Message-ID: <Ym5wVDVcNe3kOjX9@shell.armlinux.org.uk>
Date:   Sun, 1 May 2022 12:34:44 +0100
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Marcin Wojtas <mw@...ihalf.com>
Cc:     Baruch Siach <baruch@...s.co.il>, netdev <netdev@...r.kernel.org>,
        Baruch Siach <baruch.siach@...lu.com>
Subject: Re: [PATCH] net: mvpp2: add delay at the end of .mac_prepare

On Thu, Apr 28, 2022 at 10:59:59AM +0200, Marcin Wojtas wrote:
> Hi Baruch,
> 
> Thank you for the patch and debug effort, however at first glance it
> seems that adding delay may be a work-around and cover an actual root
> cause (maybe Russell will have more input here).

Please note I'm on a boat suffering diesel bug (means I'm running off
limited battery power which has to last until Wednesday for more vital
services, so I'm only around sporadically as the situation permits.
It's basically exactly an Apollo 13 situation - everything's turned
off except when absolutely required!)

Early revisions of the 88x3310 firmware have problems when switching
between the different MAC-side link modes. When this occurs, the PHY
firmware flashes one (iirc yellow) LED rapidly and refuses to link.

The answer is not to add random delays to the MAC driver, but get
the firmware of the MAC updated to something way less buggy - and
those early firmwares do contain a lot of bugs.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!