Hello Andrew, > From: Andrew Lunn, Sent: Wednesday, September 27, 2023 9:11 PM > > > Yes, the original version was tested on Spider board. > > The original version's MDC frequency was 25MHz. > > And the PHY (Marvell 88E2110) on Spider board can use such frequency, > > IIUC because the MDC period is 35 ns (so 28.57143MHz). > > 25MHz is way above anything i've tested. > > > However, I don't know why this setting cannot work on the Starter Kit board > > because the board also has the same PHY. I guess that this is related to > > board design, especially voltage of I/O (Spider = 1.8V, Starter Kit = 3.3V). > > I've had boards which will not work at 2.5Mhz until the pull up > resistor was changed to make the waveform compliant. So it probably is > related to the board. I got it. > > Anyway, changing the MDC frequency from 25MHz to 2.5MHz works correctly on > > both Spider and Starter Kit. So, I would like to apply the v3 patch [1] for safe. > > O.K. That makes sense. If you want to support the higher speed, you > could implement the device tree property: > > > clock-frequency: > description: > Desired MDIO bus clock frequency in Hz. Values greater than IEEE 802.3 > defined 2.5MHz should only be used when all devices on the bus support > the given clock speed. Thank you for the information. If I need to support the higher speed, I'll implement such a code with this device tree property. Best regards, Yoshihiro Shimoda > Andrew
