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

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Date:   Thu, 23 Nov 2023 11:34:32 +0100
From:   Wojciech Drewek <wojciech.drewek@...el.com>
To:     Furong Xu <0x1207@...il.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 23.11.2023 11:24, Furong Xu wrote:
> 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.

I would add this information the commit message.

> 
>>>
>>> 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);
>>>  }
>>>    
>