Message-ID: <A001080B-2DC8-48D9-BD82-8276A9B3BE3D@axis.com>
Date:   Mon, 21 Nov 2016 15:43:43 +0000
From:   Lars Persson <lars.persson@...s.com>
To:     Joao Pinto <Joao.Pinto@...opsys.com>
CC:     Giuseppe CAVALLARO <peppe.cavallaro@...com>,
        Rayagond Kokatanur <rayagond@...avyalabs.com>,
        Rabin Vincent <rabin@....in>, mued dib <kreptor@...il.com>,
        David Miller <davem@...emloft.net>,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        "jiri@...lanox.com" <jiri@...lanox.com>,
        "saeedm@...lanox.com" <saeedm@...lanox.com>,
        "idosch@...lanox.com" <idosch@...lanox.com>,
        netdev <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "CARLOS.PALMINHA@...opsys.com" <CARLOS.PALMINHA@...opsys.com>,
        Andreas Irestål <andire@...s.com>,
        "alexandre.torgue@...com" <alexandre.torgue@...com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: Synopsys Ethernet QoS Driver



> 21 nov. 2016 kl. 16:06 skrev Joao Pinto <Joao.Pinto@...opsys.com>:
> 
>> On 21-11-2016 14:25, Giuseppe CAVALLARO wrote:
>>> On 11/21/2016 2:28 PM, Lars Persson wrote:
>>> 
>>> 
>>>> 21 nov. 2016 kl. 13:53 skrev Giuseppe CAVALLARO <peppe.cavallaro@...com>:
>>>> 
>>>> Hello Joao
>>>> 
>>>>> On 11/21/2016 1:32 PM, Joao Pinto wrote:
>>>>> Hello,
>>>>> 
>>>>>>> On 21-11-2016 05:29, Rayagond Kokatanur wrote:
>>>>>>>> On Sat, Nov 19, 2016 at 7:26 PM, Rabin Vincent <rabin@....in> wrote:
>>>>>>>> On Fri, Nov 18, 2016 at 02:20:27PM +0000, Joao Pinto wrote:
>>>>>>>> For now we are interesting in improving the synopsys QoS driver under
>>>>>>>> /nect/ethernet/synopsys. For now the driver structure consists of a
>>>>>>>> single file
>>>>>>>> called dwc_eth_qos.c, containing synopsys ethernet qos common ops and
>>>>>>>> platform
>>>>>>>> related stuff.
>>>>>>>> 
>>>>>>>> Our strategy would be:
>>>>>>>> 
>>>>>>>> a) Implement a platform glue driver (dwc_eth_qos_pltfm.c)
>>>>>>>> b) Implement a pci glue driver (dwc_eth_qos_pci.c)
>>>>>>>> c) Implement a "core driver" (dwc_eth_qos.c) that would only have
>>>>>>>> Ethernet QoS
>>>>>>>> related stuff to be reused by the platform / pci drivers
>>>>>>>> d) Add a set of features to the "core driver" that we have available
>>>>>>>> internally
>>>>>>> 
>>>>>>> Note that there are actually two drivers in mainline for this hardware:
>>>>>>> 
>>>>>>> drivers/net/ethernet/synopsis/
>>>>>>> drivers/net/ethernet/stmicro/stmmac/
>>>>>> 
>>>>>> Yes the later driver (drivers/net/ethernet/stmicro/stmmac/) supports
>>>>>> both 3.x and 4.x. It has glue layer for pci, platform, core etc,
>>>>>> please refer this driver once before you start.
>>>>>> 
>>>>>> You can start adding missing feature of 4.x in stmmac driver.
>>>>> 
>>>>> Thanks you all for all the info.
>>>>> Well, I think we are in a good position to organize the ethernet drivers
>>>>> concerning Synopsys IPs.
>>>>> 
>>>>> First of all, in my opinion, it does not make sense to have a ethernet/synopsis
>>>>> (typo :)) when ethernet/stmicro is also for a synopsys IP. If we have another
>>>>> vendor using the same IP it should be able to reuse the commonn operations. But
>>>>> I would put that discussion for later :)
>>>>> 
>>>>> For now I suggest that for we create ethernet/qos and create there a folder
>>>>> called dwc (designware controller) where all the synopsys qos IP specific code
>>>>> in order to be reused for example by ethernet/stmicro/stmmac/. We just have to
>>>>> figure out a clean interface for "client drivers" like stmmac to interact with
>>>>> the new qos driver.
>>>>> 
>>>>> What do you think about this approach?
>>>> 
>>>> The stmmac drivers run since many years on several platforms
>>>> (sh4, stm32, arm, x86, mips ...) and it supports an huge of amount of
>>>> configurations starting from 3.1x to 3.7x databooks.
>>>> 
>>>> It also supports QoS hardware; for example, 4.00a, 4.10a and 4.20a
>>>> are fully working.
>>>> 
>>>> Also the stmmac has platform, device-tree and pcie supports and
>>>> a lot of maintained glue-logic files.
>>>> 
>>>> It is fully documented inside the kernel tree.
>>>> 
>>>> I am happy to have new enhancements from other developers.
>>>> So, on my side, if you want to spend your time on improving it on your
>>>> platforms please feel free to do it!
>>>> 
>>>> Concerning the stmicro/stmmac naming, these come from a really old
>>>> story and have no issue to adopt new folder/file names.
>>>> 
>>>> I am also open to merge fixes and changes from ethernet/synopsis.
>>>> I want to point you on some benchmarks made by Alex some months ago
>>>> (IIRC) that showed an stmmac winner (due to the several optimizations
>>>> analyzed and reviewed in this mailing list).
>>>> 
>>>> Peppe
>>>> 
>>> 
>>> Hello Joao and others,
>>> 
> 
> Hi Lars,
> 
>>> As the maintainer of dwc_eth_qos.c I prefer also that we put efforts on the
>>> most mature driver, the stmmac.
>>> 
>>> I hope that the code can migrate into an ethernet/synopsys folder to keep the
>>> convention of naming the folder after the vendor. This makes it easy for
>>> others to find the driver.
>>> 
>>> The dwc_eth_qos.c will eventually be removed and its DT binding interface can
>>> then be implemented in the stmmac driver.
> 
> So your ideia is to pick the ethernet/stmmac and rename it to ethernet/synopsys
> and try to improve the structure and add the missing QoS features to it?

Indeed this is what I prefer.

> 
>> 
>> Thanks Lars, I will be happy to support all you on this transition
>> and I agree on renaming all.
>> 
>> peppe
>> 
>> 
>>> - Lars
>>> 
>>>>> 
>>>>> 
>>>>>> 
>>>>>>> 
>>>>>>> (See http://lists.openwall.net/netdev/2016/02/29/127)
>>>>>>> 
>>>>>>> The former only supports 4.x of the hardware.
>>>>>>> 
>>>>>>> The later supports 4.x and 3.x and already has a platform glue driver
>>>>>>> with support for several platforms, a PCI glue driver, and a core driver
>>>>>>> with several features not present in the former (for example: TX/RX
>>>>>>> interrupt coalescing, EEE, PTP).
>>>>>>> 
>>>>>>> Have you evaluated both drivers?  Why have you decided to work on the
>>>>>>> former rather than the latter?
>>>>>> 
>>>>>> 
>>>>> 
>>>>> Thanks.
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>> 
>>> 
>> 
> 

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