netdev - Re: [Intel-wired-lan] [PATCH] e1000e: changed some expensive calls of udelay to usleep

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Date:   Fri, 8 Sep 2017 11:28:27 +0200
From:   Pavel Machek <pavel@....cz>
To:     "Brown, Aaron F" <aaron.f.brown@...el.com>
Cc:     Matthew Tan <matthew.tan_1@....com>,
        "intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>,
        "michael.kardonik@....com" <michael.kardonik@....com>,
        "Williams, Mitch A" <mitch.a.williams@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [Intel-wired-lan] [PATCH] e1000e: changed some expensive calls
 of udelay to usleep_range

On Thu 2017-09-07 22:19:47, Brown, Aaron F wrote:
> > From: Intel-wired-lan [mailto:intel-wired-lan-bounces@...osl.org] On
> > Behalf Of Pavel Machek
> > Sent: Monday, September 4, 2017 9:26 AM
> > To: Matthew Tan <matthew.tan_1@....com>
> > Cc: michael.kardonik@....com; Williams, Mitch A
> > <mitch.a.williams@...el.com>; linux-kernel@...r.kernel.org;
> > john.ronciak@...el.com; intel-wired-lan@...ts.osuosl.org;
> > netdev@...r.kernel.org
> > Subject: Re: [Intel-wired-lan] [PATCH] e1000e: changed some expensive calls
> > of udelay to usleep_range
> > 
> > Hi!
> > 
> > > @@ -183,7 +183,7 @@ s32 e1000e_read_phy_reg_mdic(struct e1000_hw
> > *hw, u32 offset, u16 *data)
> > >  	 * reading duplicate data in the next MDIC transaction.
> > >  	 */
> > >  	if (hw->mac.type == e1000_pch2lan)
> > > -		udelay(100);
> > > +		usleep_range(90, 100);
> > >
> > >  	return 0;
> > >  }
> > 
> > Can you explain why shortening the delay is acceptable here?
> 
> Maybe it's not.
> 
> This patch is causing speed / duplex tests to fail on several of my test systems.  Specifically a Lenova laptop with an 82577 and a NUC with an i218 (though that does not mean it is limited to those or that it's not related to the individual link partner.)
>

Ok, this should be quite easy to verify -- just adjust all the ranges
to be >= original ones.

Thanks,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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