netdev - RE: [PATCH v3 2/3] mlxbf_gige: Fix intermittent no ip issue

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Date: Fri, 13 Oct 2023 15:00:07 +0000
From: Asmaa Mnebhi <asmaa@...dia.com>
To: Florian Fainelli <f.fainelli@...il.com>, "davem@...emloft.net"
	<davem@...emloft.net>, "edumazet@...gle.com" <edumazet@...gle.com>,
	"kuba@...nel.org" <kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>,
	"olteanv@...il.com" <olteanv@...il.com>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>, David Thompson
	<davthompson@...dia.com>
Subject: RE: [PATCH v3 2/3] mlxbf_gige: Fix intermittent no ip issue



> > Although the link is up, there is no ip assigned on a setup with high
> > background traffic. Nothing is transmitted nor received.
> > The RX error count keeps on increasing. After several minutes, the RX
> > error count stagnates and the GigE interface finally gets an ip.
> >
> > The issue is in the mlxbf_gige_rx_init function. As soon as the RX DMA
> > is enabled, the RX CI reaches the max of 128, and it becomes equal to
> > RX PI. RX CI doesn't decrease since the code hasn't ran phy_start yet.
> >
> > The solution is to move the rx init after phy_start.
> >
> > Fixes: f92e1869d74e ("Add Mellanox BlueField Gigabit Ethernet driver")
> > Signed-off-by: Asmaa Mnebhi <asmaa@...dia.com>
> > Reviewed-by: David Thompson <davthompson@...dia.com>
> 
> This seems fine, but your description of the problem still looks like there may
> be a more fundamental ordering issue when you enable your RX pipe here.
> 
> It seems to me like you should enable it from "inner" as in closest to the
> CPU/DMA subsystem towards "outer" which is the MAC and finally the PHY.
> 
> It should be fine to enable your RX DMA as long as you keep the MAC's RX
> disabled, and then you can enable your MAC's RX enable and later start the
> PHY.

Thanks for your feedback Florian. I will take a look and address your comments shortly. Sorry for the delayed response, I was OOO.