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From:   Joel Stanley <joel@jms.id.au>
Date:   Wed, 14 Oct 2020 06:41:21 +0000
Message-ID: <CACPK8Xe_O44BUaPCEm2j3ZN+d4q6JbjEttLsiCLbWF6GnaqSPg@mail.gmail.com>
Subject: Re: [PATCH 1/1] net: ftgmac100: Fix Aspeed ast2600 TX hang issue
To:     Dylan Hung <dylan_hung@aspeedtech.com>
Cc:     "David S . Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, netdev@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Po-Yu Chuang <ratbert@faraday-tech.com>,
        linux-aspeed <linux-aspeed@lists.ozlabs.org>,
        OpenBMC Maillist <openbmc@lists.ozlabs.org>,
        BMC-SW <BMC-SW@aspeedtech.com>
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On Wed, 14 Oct 2020 at 06:07, Dylan Hung <dylan_hung@aspeedtech.com> wrote:
>
> The new HW arbitration feature on Aspeed ast2600 will cause MAC TX to
> hang when handling scatter-gather DMA.  Disable the problematic feature
> by setting MAC register 0x58 bit28 and bit27.

Hi Dylan,

What are the symptoms of this issue? We are seeing this on our systems:

[29376.090637] WARNING: CPU: 0 PID: 9 at net/sched/sch_generic.c:442
dev_watchdog+0x2f0/0x2f4
[29376.099898] NETDEV WATCHDOG: eth0 (ftgmac100): transmit queue 0 timed out

> Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com>

This fixes support for the ast2600, so we can put:

Fixes: 39bfab8844a0 ("net: ftgmac100: Add support for DT phy-handle property")

Reviewed-by: Joel Stanley <joel@jms.id.au>

> ---
>  drivers/net/ethernet/faraday/ftgmac100.c | 5 +++++
>  drivers/net/ethernet/faraday/ftgmac100.h | 8 ++++++++
>  2 files changed, 13 insertions(+)
>
> diff --git a/drivers/net/ethernet/faraday/ftgmac100.c b/drivers/net/ethernet/faraday/ftgmac100.c
> index 87236206366f..00024dd41147 100644
> --- a/drivers/net/ethernet/faraday/ftgmac100.c
> +++ b/drivers/net/ethernet/faraday/ftgmac100.c
> @@ -1817,6 +1817,11 @@ static int ftgmac100_probe(struct platform_device *pdev)
>                 priv->rxdes0_edorr_mask = BIT(30);
>                 priv->txdes0_edotr_mask = BIT(30);
>                 priv->is_aspeed = true;
> +               /* Disable ast2600 problematic HW arbitration */
> +               if (of_device_is_compatible(np, "aspeed,ast2600-mac")) {
> +                       iowrite32(FTGMAC100_TM_DEFAULT,
> +                                 priv->base + FTGMAC100_OFFSET_TM);
> +               }
>         } else {
>                 priv->rxdes0_edorr_mask = BIT(15);
>                 priv->txdes0_edotr_mask = BIT(15);
> diff --git a/drivers/net/ethernet/faraday/ftgmac100.h b/drivers/net/ethernet/faraday/ftgmac100.h
> index e5876a3fda91..63b3e02fab16 100644
> --- a/drivers/net/ethernet/faraday/ftgmac100.h
> +++ b/drivers/net/ethernet/faraday/ftgmac100.h
> @@ -169,6 +169,14 @@
>  #define FTGMAC100_MACCR_FAST_MODE      (1 << 19)
>  #define FTGMAC100_MACCR_SW_RST         (1 << 31)
>
> +/*
> + * test mode control register
> + */
> +#define FTGMAC100_TM_RQ_TX_VALID_DIS (1 << 28)
> +#define FTGMAC100_TM_RQ_RR_IDLE_PREV (1 << 27)
> +#define FTGMAC100_TM_DEFAULT                                                   \
> +       (FTGMAC100_TM_RQ_TX_VALID_DIS | FTGMAC100_TM_RQ_RR_IDLE_PREV)

Will aspeed issue an updated datasheet with this register documented?


> +
>  /*
>   * PHY control register
>   */
> --
> 2.17.1
>