linux-kernel - Re: [PATCH v3 3/3] net/phy: micrel: Center FLP timing at 16ms

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Message-ID: <557227A7.2080603@ni.com>
Date:	Fri, 05 Jun 2015 17:50:15 -0500
From:	Jaeden Amero <jaeden.amero@...com>
To:	Florian Fainelli <f.fainelli@...il.com>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/3] net/phy: micrel: Center FLP timing at 16ms

On 06/05/2015 05:43 PM, Florian Fainelli wrote:
> On 05/06/15 15:40, Jaeden Amero wrote:
>> Link failures have been observed when using the KSZ9031 with HP 1810-8G
>> and HP 1910-8G network switches. Center the FLP timing at 16ms to help
>> avoid intermittent link failures.
>>
>> From the KSZ9031RNX and KSZ9031MNX data sheets revision 2.2, section
>> "Auto-Negotiation Timing":
>> 	The KSZ9031[RNX or MNX] Fast Link Pulse (FLP) burst-to-burst
>> 	transmit timing for Auto-Negotiation defaults to 8ms. IEEE 802.3
>> 	Standard specifies this timing to be 16ms +/-8ms. Some PHY link
>> 	partners need to receive the FLP with 16ms centered timing;
>> 	otherwise, there can be intermittent link failures and long
>> 	link-up times.
>>
>> 	After KSZ9031[RNX or MNX] power-up/reset, program the following
>> 	register sequence to set the FLP timing to 16ms
>>
>> 	Write Register Dh = 0x0000 // Set up register address for MMD – Device Address 0h
>> 	Write Register Eh = 0x0004 // Select Register 4h of MMD – Device Address 0h
>> 	Write Register Dh = 0x4000 // Select register data for MMD – Device Address 0h, Register 4h
>> 	Write Register Eh = 0x0006 // Write value 0x0006 to MMD – Device Address 0h, Register 4h
>> 	Write Register Dh = 0x0000 // Set up register address for MMD – Device Address 0h
>> 	Write Register Eh = 0x0003 // Select Register 3h of MMD – Device Address 0h
>> 	Write Register Dh = 0x4000 // Select register data for MMD – Device Address 0h, Register 3h
>> 	Write Register Eh = 0x1A80 // Write value 0x1A80 to MMD – Device Address 0h, Register 3h
>> 	Write Register 0h, Bit [9] = 1 // Restart Auto-Negotiation
> 
> Quoting a portion of the data-sheet on how to do this programming is
> very strange considering that the code is going to be the reference, not
> the commit message.

I included it for lack of something better to quote that explained
which values to set when. I'd be happy to revise the message as this
appears too strange.

> Other than that, this looks reasonable.

Thanks very much for the review.

Cheers,
Jaeden
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