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Subject: Re: [PATCH] ixgbe: Wait for 1ms, not 1us, after RST
To: dan.streetman@canonical.com, Jeff Kirsher <jeffrey.t.kirsher@intel.com>
References: <1445904971-9442-1-git-send-email-dan.streetman@canonical.com>
Cc: Jesse Brandeburg <jesse.brandeburg@intel.com>,
        Shannon Nelson <shannon.nelson@intel.com>,
        Carolyn Wyborny <carolyn.wyborny@intel.com>,
        Don Skidmore <donald.c.skidmore@intel.com>,
        Matthew Vick <matthew.vick@intel.com>,
        John Ronciak <john.ronciak@intel.com>,
        Mitch Williams <mitch.a.williams@intel.com>,
        intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, Dan Streetman <ddstreet@ieee.org>
From: Peter Hurley <peter@hurleysoftware.com>
Message-ID: <562FBB01.3080901@hurleysoftware.com>
Date: Tue, 27 Oct 2015 13:57:21 -0400
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Hi Dan,

On 10/26/2015 08:16 PM, dan.streetman@canonical.com wrote:
> From: Dan Streetman <dan.streetman@canonical.com>
> 
> The driver currently waits 1us after issuing a RST, but the spec
> requires it to wait 1ms.
> 
> Signed-off-by: Dan Streetman <dan.streetman@canonical.com>
> Signed-off-by: Dan Streetman <ddstreet@ieee.org>
> ---
>  drivers/net/ethernet/intel/ixgbe/ixgbe_x540.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_x540.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_x540.c
> index 4e75843..147bc65 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_x540.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_x540.c
> @@ -113,7 +113,12 @@ mac_reset_top:
>  
>  	/* Poll for reset bit to self-clear indicating reset is complete */
>  	for (i = 0; i < 10; i++) {
> -		udelay(1);
> +		/* sec 8.2.4.1.1 :
> +		 * programmers must wait approximately 1 ms after setting before
> +		 * attempting to check if the bit has cleared or to access (read
> +		 * or write) any other device register.
> +		 */
> +		mdelay(1);

Since ixgbe_reset_hw_x540() goes on to msleep(100) immediately after this
busy-wait loop, this should instead be:

		msleep(1);

Regards,
Peter Hurley


>  		ctrl = IXGBE_READ_REG(hw, IXGBE_CTRL);
>  		if (!(ctrl & IXGBE_CTRL_RST_MASK))
>  			break;
>