Date:   Mon, 21 Nov 2016 15:06:23 +0000
From:   Joao Pinto <Joao.Pinto@...opsys.com>
To:     Giuseppe CAVALLARO <peppe.cavallaro@...com>,
        Lars Persson <lars.persson@...s.com>
CC:     Joao Pinto <Joao.Pinto@...opsys.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

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?


> 
> 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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