On Mon, May 11, 2020 at 04:13:10PM +0200, Oleksij Rempel wrote: > > I continue to work on TJA11xx PHY and need to export some additional > cable diagnostic/link stability information: Signal Quality Index (SQI). > The PHY data sheet describes it as following [1]: > ================================================================================ > 6.10.3 Link stability > > The signal-to-noise ratio is the parameter used to estimate link > stability. The PMA Receive function monitors the signal-to-noise ratio > continuously. Once the signal-to-noise ratio falls below a configurable > threshold (SQI_FAILLIMIT), the link status is set to FAIL and > communication is interrupted. The TJA1100 allows for adjusting the > sensitivity of the PMA Receive function by configuring this threshold. > The microcontroller can always check the current value of the > signal-to-noise ratio via the SMI, allowing it to track a possible > degradation in link stability. > ================================================================================ > > Since this functionality is present at least on TJA11xx PHYs and > mandatory according to Open Alliance[2], I hope this functionality is > present on other 100/1000Base-T1 PHYs. So may be some common abstraction > is possible. What would be the best place to provide it for the user > space? According to the [2] SQI, is the part of Dynamic Channel Quality > (DCQ) together with Mean Square Error (MSE) and Peak MSE value (pMSE).
IIUC these would be read-only parameters describing current state of the link which can be queried at any time. If this is the case, adding them as attributes to ETHTOOL_MSG_LINKSTATE_GET_REPLY message seems most fitting. As for getting / setting the threshold, perhaps ETHTOOL_MSG_LINKINFO_GET and ETHTOOL_MSG_LINKINFO_SET. Unless you expect more configurable parameters like this in which case we may want to consider adding new request type (e.g. link params or link management). Michal
