netdev - Re: [PATCH net 0/2] aqc111: Thermal throttling feature

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Date:   Wed, 12 Dec 2018 10:15:04 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Igor Russkikh <Igor.Russkikh@...antia.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Cc:     Dmitry Bezrukov <Dmitry.Bezrukov@...antia.com>, andrew@...n.ch
Subject: Re: [PATCH net 0/2] aqc111: Thermal throttling feature

On 12/12/18 5:54 AM, Igor Russkikh wrote:
> 
> 
> On 12.12.2018 16:50, Igor Russkikh wrote:
>> This patches introduce the thermal throttling feature to prevent possible
>> heat damage to the hardware.
>>
>> Dmitry Bezrukov (2):
>>   net: usb: aqc111: Add read_mdio operation
>>   net: usb: aqc111: Support for thermal throttling feature
>>
>>  drivers/net/usb/aqc111.c | 83 ++++++++++++++++++++++++++++++++++++++++
>>  drivers/net/usb/aqc111.h | 19 +++++++++
>>  2 files changed, 102 insertions(+)
>>
> 
> Hi David, all,
> 
> This is of course designated for the "net-next" tree.
> 
> I'll resubmit this after review.

The idea of having the PHY/network device as a cooling agent is
something valuable, but as Andrew pointed out, you need to expose this
as a standard HWMON device, and you need to let user-space implement the
appropriate thermal policy, not do that in the network driver underneath
the user's feet with no feedback other than link dropped, got
re-negotiated at a different speed. How would one be able to
differentiate those events from a faulty link partner for instance?

None of what you are doing here is specific to your device driver and
the policy of downgrading the link speed to lower the thermal budget is
something that is nearly universally applicable to all network
equipments because higher speeds just require higher power.
-- 
Florian