linux-kernel - Re: [PATCH 1/4] net: macb: Check MDIO state before read/write and use timeouts

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Message-ID: <20181031134810.GD20889@lunn.ch>
Date:   Wed, 31 Oct 2018 14:48:10 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Harini Katakam <harini.katakam@...inx.com>
Cc:     nicolas.ferre@...rochip.com, davem@...emloft.net,
        claudiu.beznea@...rochip.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, michal.simek@...inx.com,
        harinikatakamlinux@...il.com, Harini Katakam <harinik@...inx.com>,
        Shubhrajyoti Datta <shubhrajyoti.datta@...inx.com>,
        Sai Pavan Boddu <sai.pavan.boddu@...inx.com>
Subject: Re: [PATCH 1/4] net: macb: Check MDIO state before read/write and
 use timeouts

On Wed, Oct 31, 2018 at 09:10:20AM +0530, Harini Katakam wrote:
> From: Harini Katakam <harinik@...inx.com>
> 
> Replace the while loop in MDIO read/write functions with a timeout.
> In addition, add a check for MDIO bus busy before initiating a new
> operation as well to make sure there is no ongoing MDIO operation.
> 
> Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@...inx.com>
> Signed-off-by: Sai Pavan Boddu <sai.pavan.boddu@...inx.com>
> Signed-off-by: Harini Katakam <harinik@...inx.com>
> ---
> Changes form RFC:
> Cleaned up timeout implementation and moved it to a helper.
> 
>  drivers/net/ethernet/cadence/macb_main.c | 44 +++++++++++++++++++++++++++-----
>  1 file changed, 38 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index 0acaef3..b4e26c1 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -318,10 +318,36 @@ static void macb_get_hwaddr(struct macb *bp)
>  	eth_hw_addr_random(bp->dev);
>  }
>  
> +static int macb_mdio_wait_for_idle(struct macb *bp)
> +{
> +	ulong timeout;
> +
> +	timeout = jiffies + msecs_to_jiffies(1000);
> +	/* wait for end of transfer */
> +	while (1) {
> +		if (MACB_BFEXT(IDLE, macb_readl(bp, NSR)))
> +			break;
> +
> +		if (time_after_eq(jiffies, timeout)) {
> +			netdev_err(bp->dev, "wait for end of transfer timed out\n");
> +			return -ETIMEDOUT;
> +		}
> +
> +		cpu_relax();
> +	}
> +
> +	return 0;
> +}

Hi Harini

Could you make use of readx_poll_timeout(). You will need to add a
helper for the read of the register, since readx_poll_timeout() only
allows one parameter.

Otherwise, this looks O.K.

	   Andrew