On Thu, 2016-11-24 at 18:05 +0100, Martin Blumenstingl wrote: > On Thu, Nov 24, 2016 at 4:56 PM, Jerome Brunet <jbrunet@xxxxxxxxxxxx> > wrote: > > > > 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")? > > > > Actually you can skip the part which activate the Tx-delay on the > > phy > > by setting "phy-mode = "rgmii-id" instead of "rgmii" > > > > phy->interface will no longer be PHY_INTERFACE_MODE_RGMII > > but PHY_INTERFACE_MODE_RGMII_ID. > unfortunately this is not true for RTL8211F (I did my previous tests > with the same expectation in mind)! > the code seems to suggest that TX-delay is disabled whenever mode != > PHY_INTERFACE_MODE_RGMII. > BUT: on my device RTL8211F_TX_DELAY is set even before > "phy_write(phydev, 0x11, reg);"! Thx a lot for pointing this out. I wrongly assumed that is was off by default. It turns out it is ON on the OdroidC2 as well. So I re-did all my test: On the OdroidC2, as long as eee is not disabled (using ethtool or through my patch) I can't get iperf to work properly. Disabling EEE, the link works for the following configurations: PHY TX Delay bit set : MAC delay 0ns, 2ns. PHY TX Delay bit cleared : MAC delay 2ns, 4ns. This seems to confirm that the PHY adds a 2ns delay when the bit is set. I could not test on my MXQPRO2.1 ... the PHY is no longer found during the boot. Something died overnight :( > > Based on what I found it seems that rgmii-id, rgmii-txid and > rgmii-rxid are supposed to be handled by the PHY. > That would mean that we have two problems here: > 1) drivers/net/phy/realtek.c:rtl8211f_config_init should check for > PHY_INTERFACE_MODE_RGMII_ID or PHY_INTERFACE_MODE_RGMII_TXID and > enable the TX-delay in that case - otherwise explicitly disable it > 2) dwmac-meson8b.c should only use the configured TX-delay for > PHY_INTERFACE_MODE_RGMII > @Florian: could you please share your thoughts on this (who handles > the TX delay in which case)? > > > Regards, > Martin -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
