linux-kernel - Re: [PATCH] e1000e: changed some expensive calls of udelay to usleep

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Message-ID: <20170904162555.GB21849@amd>
Date:   Mon, 4 Sep 2017 18:25:55 +0200
From:   Pavel Machek <pavel@....cz>
To:     Matthew Tan <matthew.tan_1@....com>
Cc:     jeffrey.t.kirsher@...el.com, michael.kardonik@....com,
        carolyn.wyborny@...el.com, donald.c.skidmore@...el.com,
        bruce.w.allan@...el.com, john.ronciak@...el.com,
        mitch.a.williams@...el.com, intel-wired-lan@...ts.osuosl.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [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?
										
> @@ -246,7 +246,7 @@ s32 e1000e_write_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, 110);
>  
>  	return 0;
>  }

And here?
										Pavel

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

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