netdev - Re: [PATCH] Re: still having r8169 woes with XID 18000000

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Date:	Sat, 05 Jun 2010 11:13:21 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Timo Teräs <timo.teras@....fi>
Cc:	Phil Sutter <phil@....cc>,
	françois romieu <romieu@...zoreil.com>,
	netdev@...r.kernel.org
Subject: Re: [PATCH] Re: still having r8169 woes with XID 18000000

Le samedi 05 juin 2010 à 10:39 +0300, Timo Teräs a écrit :

> Ok, I compared Realtek's and the in-tree driver. The only essential
> difference is that Realtek driver uses udelay(100) in mdio_write()'s
> busy polling loop where as the in-tree uses udelay(25). And that seems
> to be the magic difference! Using udelay(100) fixes this!
> 
> I'm guessing that the phy needs slight delay between consecutive
> mdio_write's even if it has advertised that the write has been
> completed. And yes, just adding a small delay in the end of mdio_write
> does seem to work too.
> 
> Francois, you think the below patch is ok? Should I send it as properly
> formatted commit?
> 
> diff --git a/drivers/net/r8169.c b/drivers/net/r8169.c
> index 217e709..6db62bf 100644
> --- a/drivers/net/r8169.c
> +++ b/drivers/net/r8169.c
> @@ -559,6 +559,7 @@ static void mdio_write(void __iomem *ioaddr,
>  			break;
>  		udelay(25);
>  	}
> +	udelay(25);
>  }
> 
>  static int mdio_read(void __iomem *ioaddr, int reg_addr)
> --

Sure this deserves an official patch with all prereqs, but please add a
comment in mdio_write() why this extra udelay(25) is needed, especially
since you say of udelay(100) 'fixes the bug'.



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