netdev - Re: [PATCH v2 net-next] net: stmmac: Add support for DWMAC5 with TSN features

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Message-ID: <cc987c04-a6f1-7fcf-ac41-e54d0900e311@synopsys.com>
Date:   Thu, 7 Dec 2017 15:56:56 +0000
From:   Jose Abreu <Jose.Abreu@...opsys.com>
To:     David Miller <davem@...emloft.net>,
        Florian Fainelli <f.fainelli@...il.com>
CC:     <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <Joao.Pinto@...opsys.com>, <peppe.cavallaro@...com>,
        <alexandre.torgue@...com>
Subject: Re: [PATCH v2 net-next] net: stmmac: Add support for DWMAC5 with TSN
 features

Hi David, Florian,

On 01-11-2017 11:48, David Miller wrote:
> From: Jose Abreu <Jose.Abreu@...opsys.com>
> Date: Fri, 27 Oct 2017 14:55:44 +0100
>
>> This adds support for IP version 5 of DWMAC. The new introduced
>> features are the Enhancements to Scheduled Traffic (EST) as
>> defined by IEEE802.1Qbv-2015 and Frame Preemption (FPE) as
>> defined by IEEE802.1Qbu.
>>
>> In order to not break previous setups all the necessary
>> configuration is only performed when GMAC5 is detected and
>> only when all the necessary parameters are available in the
>> Device Tree.
>>
>> EST:
>> The IEEE802.1Qbv-2015 defines the schedule for each of the
>> queues which makes the IP aware of traffic arrival time. This
>> information can be used to block the lower priority traffic
>> from transmission in this time window/slot.
>>
>> FPE:
>> The IEEE802.1Qbu defines a mechanism which breaks interfering
>> frames into smaller fragments shuch that we have a more efficient
>> use of network bandwidth. This needs EST enabled.
>>
>> Signed-off-by: Jose Abreu <joabreu@...opsys.com>
>> Cc: David S. Miller <davem@...emloft.net>
>> Cc: Joao Pinto <jpinto@...opsys.com>
>> Cc: Giuseppe Cavallaro <peppe.cavallaro@...com>
>> Cc: Alexandre Torgue <alexandre.torgue@...com>
>> ---
>> Changes since v1:
>> - Removed DT parsing
> This patch is pointless until something is added which turns on the
> boolean enable values.

First submission of this patch had DT bindings included to make
this configurable. I removed them following Florian input, which
I totally agree because DT describes HW and not configuration.
Current version of this patch makes this configurable by platform
data only.

This DWMAC5 is a new controller which will be available in new
NICs shortly so I think this is the best time to start thinking
about including these features. This way we will have support out
of the shelf for these new NICs ... I also must say that these
new features are a big leap forward for Quality-of-service
networking, as they allow us to specify traffic scheduling per
queue, improving not only network performance (by, for example,
reserving specific time slots for traffic that is periodic) as
well as network quality (by providing a constant bandwidth for
scheduled traffic).

David, Florian, may I ask what is in your opinion the best way to
handle the implementation of these new features?

Thanks and Best Regards,
Jose Miguel Abreu