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From: Andrew Lunn <andrew@lunn.ch>
To: Kurt Kanzenbach <kurt@linutronix.de>
Cc: Anirudha Sarangi <anirudh@xilinx.com>,
	John Linn <John.Linn@xilinx.com>,
	"David S. Miller" <davem@davemloft.net>,
	Michal Simek <michal.simek@xilinx.com>,
	Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>,
	YueHaibing <yuehaibing@huawei.com>,
	netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] net: xilinx_emaclite: recheck condition after timeout in mdio_wait()
Date: Tue, 30 Oct 2018 13:10:30 +0100	[thread overview]
Message-ID: <20181030121030.GD27873@lunn.ch> (raw)
In-Reply-To: <20181030093139.10226-3-kurt@linutronix.de>

On Tue, Oct 30, 2018 at 10:31:39AM +0100, Kurt Kanzenbach wrote:
> The function could report a false positive if it gets preempted between reading
> the XEL_MDIOCTRL_OFFSET register and checking for the timeout.  In such a case,
> the condition has to be rechecked to avoid false positives.
> 
> Therefore, check for expected condition even after the timeout occurred.
> 
> Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
> ---
>  drivers/net/ethernet/xilinx/xilinx_emaclite.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/ethernet/xilinx/xilinx_emaclite.c b/drivers/net/ethernet/xilinx/xilinx_emaclite.c
> index 639e3e99af46..957d03085bd0 100644
> --- a/drivers/net/ethernet/xilinx/xilinx_emaclite.c
> +++ b/drivers/net/ethernet/xilinx/xilinx_emaclite.c
> @@ -714,19 +714,29 @@ static irqreturn_t xemaclite_interrupt(int irq, void *dev_id)
>  static int xemaclite_mdio_wait(struct net_local *lp)
>  {
>  	unsigned long end = jiffies + 2;
> +	u32 val;
>  
>  	/* wait for the MDIO interface to not be busy or timeout
>  	 * after some time.
>  	 */
> -	while (xemaclite_readl(lp->base_addr + XEL_MDIOCTRL_OFFSET) &
> -			XEL_MDIOCTRL_MDIOSTS_MASK) {
> +	while (1) {
> +		val = xemaclite_readl(lp->base_addr + XEL_MDIOCTRL_OFFSET);

Hi Kurt

It looks like readx_poll_timeout() should work here.

   Andrew

  reply	other threads:[~2018-10-30 12:10 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-30  9:31 [PATCH 0/2] net: xlinx: mdio: recheck condition after timeout Kurt Kanzenbach
2018-10-30  9:31 ` [PATCH 1/2] net: axienet: recheck condition after timeout in mdio_wait() Kurt Kanzenbach
2018-10-30 18:25   ` David Miller
2018-10-31 13:06     ` Kurt Kanzenbach
2018-11-05  9:16     ` Sebastian Andrzej Siewior
2018-10-30  9:31 ` [PATCH 2/2] net: xilinx_emaclite: " Kurt Kanzenbach
2018-10-30 12:10   ` Andrew Lunn [this message]
2018-10-30 12:58     ` Radhey Shyam Pandey
2018-10-30 18:25   ` David Miller
2018-10-30 12:08 ` [PATCH 0/2] net: xlinx: mdio: recheck condition after timeout Andrew Lunn
2018-10-30 13:47   ` Kurt Kanzenbach

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