[net-next PATCH v1 0/2] stmmac: dwmac-meson8b: configurable RGMII TX delay

[jbrunet@baylibre.com (Jerome Brunet)]

On Thu, 2016-11-24 at 15:34 +0100, Martin Blumenstingl wrote:
> Currently the dwmac-meson8b stmmac glue driver uses a hardcoded 1/4
> cycle TX clock delay. This seems to work fine for many boards (for
> example Odroid-C2 or Amlogic's reference boards) but there are some
> others where TX traffic is simply broken.
> There are probably multiple reasons why it's working on some boards
> while it's broken on others:
> - some of Amlogic's reference boards are using a Micrel PHY
> - hardware circuit design
> - maybe more...
> 
> This raises a question though:
> Which device is supposed to enable the TX delay when both MAC and PHY
> support it? And should we implement it for each PHY / MAC separately
> or should we think about a more generic solution (currently it's not
> possible to disable the TX delay generated by the RTL8211F PHY via
> devicetree when using phy-mode "rgmii")?
> 
> iperf3 results on my Mecool BB2 board (Meson GXM, RTL8211F PHY) with
> TX clock delay disabled on the MAC (as it's enabled in the PHY
> driver).
> TX throughput was virtually zero before:
> $ iperf3 -c 192.168.1.100 -R??????????
> Connecting to host 192.168.1.100, port 5201
> Reverse mode, remote host 192.168.1.100 is sending
> [??4] local 192.168.1.206 port 52828 connected to 192.168.1.100 port
> 5201
> [ ID] Interval???????????Transfer?????Bandwidth
> [??4]???0.00-1.00???sec???108 MBytes???901
> Mbits/sec??????????????????
> [??4]???1.00-2.00???sec??94.2 MBytes???791
> Mbits/sec??????????????????
> [??4]???2.00-3.00???sec??96.5 MBytes???810
> Mbits/sec??????????????????
> [??4]???3.00-4.00???sec??96.2 MBytes???808
> Mbits/sec??????????????????
> [??4]???4.00-5.00???sec??96.6 MBytes???810
> Mbits/sec??????????????????
> [??4]???5.00-6.00???sec??96.5 MBytes???810
> Mbits/sec??????????????????
> [??4]???6.00-7.00???sec??96.6 MBytes???810
> Mbits/sec??????????????????
> [??4]???7.00-8.00???sec??96.5 MBytes???809
> Mbits/sec??????????????????
> [??4]???8.00-9.00???sec???105 MBytes???884
> Mbits/sec??????????????????
> [??4]???9.00-10.00??sec???111 MBytes???934
> Mbits/sec??????????????????
> - - - - - - - - - - - - - - - - - - - - - - - - -
> [ ID] Interval???????????Transfer?????Bandwidth???????Retr
> [??4]???0.00-10.00??sec??1000 MBytes???839
> Mbits/sec????0?????????????sender
> [??4]???0.00-10.00??sec???998 MBytes???837
> Mbits/sec??????????????????receiver
> 
> iperf Done.
> $ iperf3 -c 192.168.1.100???
> Connecting to host 192.168.1.100, port 5201
> [??4] local 192.168.1.206 port 52832 connected to 192.168.1.100 port
> 5201
> [ ID] Interval???????????Transfer?????Bandwidth???????Retr??Cwnd
> [??4]???0.00-1.01???sec??99.5 MBytes???829 Mbits/sec??117????139
> KBytes???????
> [??4]???1.01-2.00???sec???105 MBytes???884 Mbits/sec??129???70.7
> KBytes???????
> [??4]???2.00-3.01???sec???107 MBytes???889 Mbits/sec??106????187
> KBytes???????
> [??4]???3.01-4.01???sec???105 MBytes???878 Mbits/sec???92????143
> KBytes???????
> [??4]???4.01-5.00???sec???105 MBytes???882 Mbits/sec??140????129
> KBytes???????
> [??4]???5.00-6.01???sec???106 MBytes???883 Mbits/sec??115????195
> KBytes???????
> [??4]???6.01-7.00???sec???102 MBytes???863 Mbits/sec??133???70.7
> KBytes???????
> [??4]???7.00-8.01???sec???106 MBytes???884 Mbits/sec??143???97.6
> KBytes???????
> [??4]???8.01-9.01???sec???104 MBytes???875 Mbits/sec??124????107
> KBytes???????
> [??4]???9.01-10.01??sec???105 MBytes???876 Mbits/sec???90????139
> KBytes???????
> - - - - - - - - - - - - - - - - - - - - - - - - -
> [ ID] Interval???????????Transfer?????Bandwidth???????Retr
> [??4]???0.00-10.01??sec??1.02 GBytes???874
> Mbits/sec??1189?????????????sender
> [??4]???0.00-10.01??sec??1.02 GBytes???873
> Mbits/sec??????????????????receiver
> 

Cool, one more board working ;)
I tried your patch on another board (MXQ_V2.1, with sheep printed on
the PCB). It 's not improving the situation for this one unfortunately.
Actually I already tried playing with the TX delay on the MAC and PHY
but I could get any good results with the boards I have.

It is strange that we can adjust the delay by 2ns steps, when delay
seens by the phy should be 2ns ...

> iperf Done.
> 
> 
> Martin Blumenstingl (2):
> ? net: dt-bindings: add RGMII TX delay configuration to meson8b-dwmac
> ? net: stmmac: dwmac-meson8b: make the RGMII TX delay configurable
> 
> ?Documentation/devicetree/bindings/net/meson-dwmac.txt | 11
> +++++++++++
> ?drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c???| 16
> +++++++++++-----
> ?include/dt-bindings/net/dwmac-meson8b.h???????????????| 18
> ++++++++++++++++++
> ?3 files changed, 40 insertions(+), 5 deletions(-)
> ?create mode 100644 include/dt-bindings/net/dwmac-meson8b.h
>