linux-kernel - Re: [RFC PATCH 1/5] net: macb: Check MDIO state before read/write and use timeouts

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Message-ID: <20180322144716.GB24516@lunn.ch>
Date:   Thu, 22 Mar 2018 15:47:16 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     harinikatakamlinux@...il.com
Cc:     nicolas.ferre@...el.com, davem@...emloft.net,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        harinik@...inx.com, michals@...inx.com, appanad@...inx.com,
        Shubhrajyoti Datta <shubhrajyoti.datta@...inx.com>
Subject: Re: [RFC PATCH 1/5] net: macb: Check MDIO state before read/write
 and use timeouts

On Thu, Mar 22, 2018 at 07:21:36PM +0530, harinikatakamlinux@...il.com 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: Harini Katakam <harinik@...inx.com>
> ---
>  drivers/net/ethernet/cadence/macb_main.c | 54 ++++++++++++++++++++++++++++++--
>  1 file changed, 52 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index d09bd43..f4030c1 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -321,6 +321,21 @@ static int macb_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
>  {
>  	struct macb *bp = bus->priv;
>  	int value;
> +	ulong timeout;
> +
> +	timeout = jiffies + msecs_to_jiffies(1000);
> +	/* wait for end of transfer */
> +	do {
> +		if (MACB_BFEXT(IDLE, macb_readl(bp, NSR)))
> +			break;
> +
> +		cpu_relax();
> +	} while (!time_after_eq(jiffies, timeout));
> +
> +	if (time_after_eq(jiffies, timeout)) {
> +		netdev_err(bp->dev, "wait for end of transfer timed out\n");
> +		return -ETIMEDOUT;
> +	}

Hi Harini

It looks like you have repeated the same code 4 times. Please move it
into a helper function.

     Andrew