Re: Synopsys Ethernet QoS Driver

From: Joao Pinto
Date: Mon Nov 21 2016 - 08:49:03 EST

Hello Peppe,

On 21-11-2016 12:52, Giuseppe CAVALLARO wrote:
> 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.

Synopsys QoS IP is a separated hardware component, so it should be reusable by
all implementations using it and so have its own "core driver" and platform +
pci glue drivers. This is necessary for example in hardware validation, where
you prototype an IP and instantiate its drivers and test it.

Was there a strong reason to integrate QoS features directly in stmmac and not
in synopsys/dwc_eth_qos.*?

> 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.

Thanks for the information, I am going to check it out.

> 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.

Thank you for your availability!

> 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