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SubjectRe: [PATCH net-master 1/1] net: phy: dp83867: Add speed optimization feature
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On 1/31/2020 5:30 PM, Dan Murphy wrote:
> Heiner
>
> On 1/31/20 2:56 PM, Heiner Kallweit wrote:
>> On 31.01.2020 16:11, Dan Murphy wrote:
>>> Set the speed optimization bit on the DP83867 PHY.
>>> This feature can also be strapped on the 64 pin PHY devices
>>> but the 48 pin devices do not have the strap pin available to enable
>>> this feature in the hardware.  PHY team suggests to have this bit set.
>>>
>> It's ok to enable downshift by default, however it would be good to
>> make it configurable. Best implement the downshift tunable, you can
>> use the Marvell PHY driver as reference.
>> Can the number of attempts until downshifts happens be configured?
>
> Yes we can tune the number of attempts it makes to negotiate 1000Mbps
> before enabling the speed optimization.  But why would we need to
> configure the number of attempts currently it is defaulted to 4.  Is
> there a use case for this level of configurability?

Some customers may prefer a fast(er) link re-negotiation once they know
the cabling is faulty or sub-optimal. The default is usually fine, and
if you want to support the downshift ethtool tunable when net-next opens
back up, that would be a welcome addition.
--
Florian

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