netdev - RE: [net-next 05/11] i40e: fix for queue timing delays

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Date:   Mon, 27 Mar 2017 16:12:37 +0000
From:   "Wyborny, Carolyn" <carolyn.wyborny@...el.com>
To:     David Miller <davem@...emloft.net>,
        "Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "nhorman@...hat.com" <nhorman@...hat.com>,
        "sassmann@...hat.com" <sassmann@...hat.com>,
        "jogreene@...hat.com" <jogreene@...hat.com>
Subject: RE: [net-next 05/11] i40e: fix for queue timing delays

> -----Original Message-----
> From: David Miller [mailto:davem@...emloft.net]
> Sent: Saturday, March 25, 2017 8:01 PM
> To: Kirsher, Jeffrey T <jeffrey.t.kirsher@...el.com>
> Cc: Wyborny, Carolyn <carolyn.wyborny@...el.com>;
> netdev@...r.kernel.org; nhorman@...hat.com; sassmann@...hat.com;
> jogreene@...hat.com
> Subject: Re: [net-next 05/11] i40e: fix for queue timing delays
> 
> From: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
> Date: Sat, 25 Mar 2017 01:12:59 -0700
> 
> > From: Carolyn Wyborny <carolyn.wyborny@...el.com>
> >
> > This patch adds a delay to Rx queue disables to accommodate HW needs.
> >
[..]
> > +	/* HW needs up to 50ms to finish RX queue disable*/
> > +	mdelay(50);
> 
> You just polled a register which indicates that the request is finished.
> Needing futher time for the operation to complete doesn't make any
> sense.
> 
> If this is really needed, you need to explain in the commit message, in
> detail, what is really the problem here.
> 
> THanks.

It's a hw limitation, will submit an updated patch with more detail.

Thanks,

Carolyn

Carolyn Wyborny 
Linux Development 
Networking Division 
Intel Corporation