linux-kernel - Re: [PATCH net v1] net: stmmac: xgmac: Disable FPE MMC interrupts

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Date:   Thu, 23 Nov 2023 18:24:05 +0800
From:   Furong Xu <0x1207@...il.com>
To:     Wojciech Drewek <wojciech.drewek@...el.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Joao Pinto <jpinto@...opsys.com>,
        Simon Horman <horms@...nel.org>, <netdev@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <xfr@...look.com>,
        <rock.xu@....com>
Subject: Re: [PATCH net v1] net: stmmac: xgmac: Disable FPE MMC interrupts

On Thu, 23 Nov 2023 11:17:17 +0100
Wojciech Drewek <wojciech.drewek@...el.com> wrote:

> On 23.11.2023 10:35, Furong Xu wrote:
> > Commit aeb18dd07692 ("net: stmmac: xgmac: Disable MMC interrupts
> > by default") leaves the FPE(Frame Preemption) MMC interrupts enabled.
> > Now we disable FPE TX and RX interrupts too.  
> 
> Hi,
> Thanks for the patch, one question:
> Why do we have to disable them?
> 

The original commit aeb18dd07692 by Jose Abreu says:

    MMC interrupts were being enabled, which is not what we want because it
    will lead to a storm of interrupts that are not handled at all. Fix it
    by disabling all MMC interrupts for XGMAC.

> > 
> > Fixes: aeb18dd07692 ("net: stmmac: xgmac: Disable MMC interrupts by default")
> > Signed-off-by: Furong Xu <0x1207@...il.com>
> > ---
> >  drivers/net/ethernet/stmicro/stmmac/mmc_core.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/mmc_core.c b/drivers/net/ethernet/stmicro/stmmac/mmc_core.c
> > index ea4910ae0921..cdd7fbde2bfa 100644
> > --- a/drivers/net/ethernet/stmicro/stmmac/mmc_core.c
> > +++ b/drivers/net/ethernet/stmicro/stmmac/mmc_core.c
> > @@ -177,8 +177,10 @@
> >  #define MMC_XGMAC_RX_DISCARD_OCT_GB	0x1b4
> >  #define MMC_XGMAC_RX_ALIGN_ERR_PKT	0x1bc
> >  
> > +#define MMC_XGMAC_FPE_TX_INTR_MASK	0x204
> >  #define MMC_XGMAC_TX_FPE_FRAG		0x208
> >  #define MMC_XGMAC_TX_HOLD_REQ		0x20c
> > +#define MMC_XGMAC_FPE_RX_INTR_MASK	0x224
> >  #define MMC_XGMAC_RX_PKT_ASSEMBLY_ERR	0x228
> >  #define MMC_XGMAC_RX_PKT_SMD_ERR	0x22c
> >  #define MMC_XGMAC_RX_PKT_ASSEMBLY_OK	0x230
> > @@ -352,6 +354,8 @@ static void dwxgmac_mmc_intr_all_mask(void __iomem *mmcaddr)
> >  {
> >  	writel(0x0, mmcaddr + MMC_RX_INTR_MASK);
> >  	writel(0x0, mmcaddr + MMC_TX_INTR_MASK);
> > +	writel(MMC_DEFAULT_MASK, mmcaddr + MMC_XGMAC_FPE_TX_INTR_MASK);
> > +	writel(MMC_DEFAULT_MASK, mmcaddr + MMC_XGMAC_FPE_RX_INTR_MASK);
> >  	writel(MMC_DEFAULT_MASK, mmcaddr + MMC_XGMAC_RX_IPC_INTR_MASK);
> >  }
> >