Re: Synopsys Ethernet QoS Driver

From: Giuseppe CAVALLARO
Date: Mon Nov 21 2016 - 09:38:44 EST

Hello Joao

On 11/21/2016 2:48 PM, Joao Pinto wrote:
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.*?

We decided to enhance the stmmac on supporting the QoS for several
reasons; for example the common APIs that the driver already exposed and
actually suitable for other SYNP chips. Then, PTP, EEE,
S/RGMII, MMC could be shared among different chips with a minimal
effort. This meant a lot of code already ready.

For sure, the net-core, Ethtool, mdio parts were reused. Same for the
glue logic files.
For the latter, this helped to easily bring-up new platforms also
because the stmmac uses the HW cap register to auto-configure many
parts of the MAC core, DMA and modules. This helped many users, AFAIK.

For validation purpose, this is my experience, the stmmac helped
a lot because people used the same code to validate different HW
and it was easy to switch to a platform to another one in order to
verify / check if the support was ok or if a regression was introduced.
This is important for complex supports like PTP or EEE.

Hoping this can help.

Do not hesitate to contact me for further details