netdev - Re: [PATCH 1/4] amd-xgbe: Reset the PHY rx data path when mailbox command timeout

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Date:   Fri, 12 Feb 2021 12:43:46 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Shyam Sundar S K <Shyam-sundar.S-k@....com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org
Cc:     Sudheesh.Mavila@....com
Subject: Re: [PATCH 1/4] amd-xgbe: Reset the PHY rx data path when mailbox
 command timeout

On 2/12/21 12:00 PM, Shyam Sundar S K wrote:
> Sometimes mailbox commands timeout when the RX data path becomes
> unresponsive. This prevents the submission of new mailbox commands to DXIO.
> This patch identifies the timeout and resets the RX data path so that the
> next message can be submitted properly.
> 
> Signed-off-by: Sudheesh Mavila <sudheesh.mavila@....com>
> Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@....com>

I believe you need a Co-developed-by: before Sudheesh's Signed-off-by: 
if he was a co-developer.

> ---
>   drivers/net/ethernet/amd/xgbe/xgbe-common.h | 13 +++++++++++
>   drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c | 25 ++++++++++++++++++++-
>   2 files changed, 37 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-common.h b/drivers/net/ethernet/amd/xgbe/xgbe-common.h
> index b40d4377cc71..318817450fbd 100644
> --- a/drivers/net/ethernet/amd/xgbe/xgbe-common.h
> +++ b/drivers/net/ethernet/amd/xgbe/xgbe-common.h
> @@ -1279,10 +1279,18 @@
>   #define MDIO_PMA_10GBR_FECCTRL		0x00ab
>   #endif
>   
> +#ifndef MDIO_PMA_RX_CTRL1
> +#define MDIO_PMA_RX_CTRL1		0x8051
> +#endif
> +
>   #ifndef MDIO_PCS_DIG_CTRL
>   #define MDIO_PCS_DIG_CTRL		0x8000
>   #endif
>   
> +#ifndef MDIO_PCS_DIGITAL_STAT
> +#define MDIO_PCS_DIGITAL_STAT		0x8010
> +#endif
> +
>   #ifndef MDIO_AN_XNP
>   #define MDIO_AN_XNP			0x0016
>   #endif
> @@ -1358,6 +1366,7 @@
>   #define XGBE_KR_TRAINING_ENABLE		BIT(1)
>   
>   #define XGBE_PCS_CL37_BP		BIT(12)
> +#define XGBE_PCS_PSEQ_STATE_BIT		0x10

See comment below, this is a 3-bit field.

>   
>   #define XGBE_AN_CL37_INT_CMPLT		BIT(0)
>   #define XGBE_AN_CL37_INT_MASK		0x01
> @@ -1375,6 +1384,10 @@
>   #define XGBE_PMA_CDR_TRACK_EN_OFF	0x00
>   #define XGBE_PMA_CDR_TRACK_EN_ON	0x01
>   
> +#define XGBE_PMA_RX_RST_0_MASK		BIT(4)
> +#define XGBE_PMA_RX_RST_0_RESET_ON	0x10
> +#define XGBE_PMA_RX_RST_0_RESET_OFF	0x00
> +
>   /* Bit setting and getting macros
>    *  The get macro will extract the current bit field value from within
>    *  the variable
> diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c b/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c
> index 859ded0c06b0..489f1f86df99 100644
> --- a/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c
> +++ b/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c
> @@ -1953,6 +1953,24 @@ static void xgbe_phy_set_redrv_mode(struct xgbe_prv_data *pdata)
>   	xgbe_phy_put_comm_ownership(pdata);
>   }
>   
> +static void xgbe_phy_rx_reset(struct xgbe_prv_data *pdata)
> +{
> +	int reg;
> +
> +	reg = XMDIO_READ(pdata, MDIO_MMD_PCS, MDIO_PCS_DIGITAL_STAT);
> +	if (reg & XGBE_PCS_PSEQ_STATE_BIT) {

The PSEQ_STATE field is a 3 bit field and I believe you're looking for a 
POWER_GOOD state, so this should be:

	reg = XMDIO_READ_BITS(pdata, MDIO_MMD_PCS, MDIO_PCS_DIGITAL_STAT
			      XGBE_PCS_PSEQ_STATE_MASK);
	if (reg == XGBE_PCS_PSEQ_STATE_POWER_GOOD) {

where the constants define in xgbe-common.h should be:

#define XGBE_PCS_PSEQ_STATE_MASK	0x1c
#define XGBE_PCS_PSEQ_STATE_POWER_GOOD	0x10


> +		/* mailbox command timed out, reset Rx block */
> +		/* Assert reset bit for 8ns and wait for 40us */

Please combine this comment and be sure to capitalize appropriately.

> +		XMDIO_WRITE_BITS(pdata, MDIO_MMD_PMAPMD, MDIO_PMA_RX_CTRL1,
> +				 XGBE_PMA_RX_RST_0_MASK, XGBE_PMA_RX_RST_0_RESET_ON);
> +		ndelay(20);

This time doesn't match the comment of 8ns... which one is correct?

> +		XMDIO_WRITE_BITS(pdata, MDIO_MMD_PMAPMD, MDIO_PMA_RX_CTRL1,
> +				 XGBE_PMA_RX_RST_0_MASK, XGBE_PMA_RX_RST_0_RESET_OFF);
> +		usleep_range(40, 50);
> +		netif_err(pdata, link, pdata->netdev, "firmware mailbox reset performed\n");
> +	}
> +}
> +
>   static void xgbe_phy_perform_ratechange(struct xgbe_prv_data *pdata,
>   					unsigned int cmd, unsigned int sub_cmd)
>   {
> @@ -1960,9 +1978,11 @@ static void xgbe_phy_perform_ratechange(struct xgbe_prv_data *pdata,
>   	unsigned int wait;
>   
>   	/* Log if a previous command did not complete */
> -	if (XP_IOREAD_BITS(pdata, XP_DRIVER_INT_RO, STATUS))
> +	if (XP_IOREAD_BITS(pdata, XP_DRIVER_INT_RO, STATUS)) {
>   		netif_dbg(pdata, link, pdata->netdev,
>   			  "firmware mailbox not ready for command\n");
> +			xgbe_phy_rx_reset(pdata);

An extra tab here.

Thanks,
Tom

> +	}
>   
>   	/* Construct the command */
>   	XP_SET_BITS(s0, XP_DRIVER_SCRATCH_0, COMMAND, cmd);
> @@ -1984,6 +2004,9 @@ static void xgbe_phy_perform_ratechange(struct xgbe_prv_data *pdata,
>   
>   	netif_dbg(pdata, link, pdata->netdev,
>   		  "firmware mailbox command did not complete\n");
> +
> +	/* Reset on error */
> +	xgbe_phy_rx_reset(pdata);
>   }
>   
>   static void xgbe_phy_rrc(struct xgbe_prv_data *pdata)
>