Created attachment 210549 [details]
fix uart reference clock in zynq device tree files
The Zybo board uses a 100Mhz reference clock for its uarts but the device tree file indicates it's 50Mhz. Zybo boots up using whatever speed is set by u-boot but this problem becomes apparent when you attempt to change the uart speed.
The Zedboard uses a 50Mhz clock so it works properly. But, it seems most Zynq boards use 100Mhz and only the Zedboard uses 50Mhz so my proposed fix is to change the "default" reference clock in zynq-7000.dtsi to 100Mhz and then set Zedboard's ref clock to 50Mhz in zedboard.dts.
Thanks to Milan Obuch for discovering this and pointing it out to me.