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

Andrew Lunn
2018-10-31T13:48:17Z

On Wed, Oct 31, 2018 at 09:10:20AM +0530, Harini Katakam wrote:
> From: Harini Katakam <harinik@xilinx.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@xilinx.com>
> Signed-off-by: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>
> Signed-off-by: Harini Katakam <harinik@xilinx.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