Re: Synopsys Ethernet QoS Driver

From: Lars Persson
Date: Mon Nov 21 2016 - 10:43:52 EST




> 21 nov. 2016 kl. 16:06 skrev Joao Pinto <Joao.Pinto@xxxxxxxxxxxx>:
>
>> 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@xxxxxx>:
>>>>
>>>> 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@xxxxxx> 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.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>