linux-kernel - Re: [PATCH v1] net: stmmac: enable MAC after MTL configuring

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Message-ID: <20241023084910.GL402847@kernel.org>
Date: Wed, 23 Oct 2024 09:49:10 +0100
From: Simon Horman <horms@...nel.org>
To: Furong Xu <0x1207@...il.com>
Cc: 2694439648@...com, alexandre.torgue@...s.st.com, joabreu@...opsys.com,
	davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, mcoquelin.stm32@...il.com,
	netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	hailong.fan@...ngine.com
Subject: Re: [PATCH v1] net: stmmac: enable MAC after MTL configuring

On Mon, Oct 21, 2024 at 01:05:54PM +0800, Furong Xu wrote:
> On Mon, 21 Oct 2024 09:03:05 +0800, 2694439648@...com wrote:
> 
> > From: "hailong.fan" <hailong.fan@...ngine.com>
> > 
> > DMA maybe block while ETH is opening,
> > Adjust the enable sequence, put the MAC enable last
> > 
> > For example, ETH is directly connected to the switch,
> > which never power down and sends broadcast packets at regular intervals.
> > During the process of opening ETH, data may flow into the MTL FIFO,
> > once MAC RX is enabled. and then, MTL will be set, such as FIFO size.
> > Once enable DMA, There is a certain probability that DMA will read
> > incorrect data from MTL FIFO, causing DMA to hang up.
> > By read DMA_Debug_Status, you can be observed that the RPS remains at
> > a certain value forever. The correct process should be to configure
> > MAC/MTL/DMA before enabling DMA/MAC
> > 
> > Signed-off-by: hailong.fan <hailong.fan@...ngine.com>
> > 
> 
> A Fixes: tag should be added.

Also, as this patch is a fix for net, that target should be noted in the
subject.

  Subject: [PATCH v2 net] ...

Please address this and the issues raised by Furong Xu and post a v3.

> >  static void dwxgmac2_dma_stop_rx(struct stmmac_priv *priv, void __iomem *ioaddr,
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > index e21404822..c19ca62a4 100644
> > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > @@ -3437,9 +3437,6 @@ static int stmmac_hw_setup(struct net_device *dev, bool ptp_register)
> >  		priv->hw->rx_csum = 0;
> >  	}
> >  
> > -	/* Enable the MAC Rx/Tx */
> > -	stmmac_mac_set(priv, priv->ioaddr, true);
> > -
> >  	/* Set the HW DMA mode and the COE */
> >  	stmmac_dma_operation_mode(priv);
> >  
> > @@ -3523,6 +3520,9 @@ static int stmmac_hw_setup(struct net_device *dev, bool ptp_register)
> >  	/* Start the ball rolling... */
> >  	stmmac_start_all_dma(priv);
> >  
> > +	/* Enable the MAC Rx/Tx */
> > +	stmmac_mac_set(priv, priv->ioaddr, true);
> > +
> 
> This sequence fix should be applied to stmmac_xdp_open() too.
> 
> >  	stmmac_set_hw_vlan_mode(priv, priv->hw);
> >  
> >  	return 0;
> 
> It is better to split this patch into individual patches, since you are
> trying to fix an issue related to several previous commits:
> dwmac4, dwxgmac2, stmmac_hw_setup() and stmmac_xdp_open()

And each patch should have an appropriate Fixes tag.

-- 
pw-bot: changes-requested