linux-kernel - Re: [PATCH net-next 1/3] net: stmmac: xgmac: Disable RX FIFO Overflow interrupts

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Message-ID: <bef4d761-8909-4f90-8822-8c344291cb93@lunn.ch>
Date: Mon, 14 Jul 2025 15:34:47 +0200
From: Andrew Lunn <andrew@...n.ch>
To: rohan.g.thomas@...era.com
Cc: Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Serge Semin <fancer.lancer@...il.com>,
	Romain Gantois <romain.gantois@...tlin.com>, netdev@...r.kernel.org,
	linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Matthew Gerlach <matthew.gerlach@...era.com>
Subject: Re: [PATCH net-next 1/3] net: stmmac: xgmac: Disable RX FIFO
 Overflow interrupts

On Mon, Jul 14, 2025 at 03:59:17PM +0800, Rohan G Thomas via B4 Relay wrote:
> From: Rohan G Thomas <rohan.g.thomas@...era.com>
> 
> Enabling RX FIFO Overflow interrupts is counterproductive
> and causes an interrupt storm when RX FIFO overflows.
> Disabling this interrupt has no side effect and eliminates
> interrupt storms when the RX FIFO overflows.
> 
> Commit 8a7cb245cf28 ("net: stmmac: Do not enable RX FIFO
> overflow interrupts") disables RX FIFO overflow interrupts
> for DWMAC4 IP and removes the corresponding handling of
> this interrupt. This patch is doing the same thing for
> XGMAC IP.
> 
> Signed-off-by: Rohan G Thomas <rohan.g.thomas@...era.com>
> Reviewed-by: Matthew Gerlach <matthew.gerlach@...era.com>

Please take a read of:

https://www.kernel.org/doc/html/latest/process/maintainer-netdev.html

This appears to be a fixed, so the Subject: line should indicate this.
Please also include a Fixes: tag, and Cc: stable.

> ---
>  drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
> index 5dcc95bc0ad28b756accf9670c5fa00aa94fcfe3..7201a38842651a865493fce0cefe757d6ae9bafa 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
> @@ -203,10 +203,6 @@ static void dwxgmac2_dma_rx_mode(struct stmmac_priv *priv, void __iomem *ioaddr,
>  	}
>  
>  	writel(value, ioaddr + XGMAC_MTL_RXQ_OPMODE(channel));
> -
> -	/* Enable MTL RX overflow */
> -	value = readl(ioaddr + XGMAC_MTL_QINTEN(channel));
> -	writel(value | XGMAC_RXOIE, ioaddr + XGMAC_MTL_QINTEN(channel));

What is the reset default? Would it make sense to explicitly disable
it, rather than never enable it? What does 8a7cb245cf28 do?

    Andrew

---
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