I've hit this on the A64 but it is likely present on other Allwinner chips.
I'm been digging around in Pine64 Bluetooth as to why it keeps
failing. One reason is that it is constantly getting overruns. I
believe the Pine64 Realtek code is only running on the UART at 115,200
and our Broadcom hardware is running at 921,600. The problem here is
that BT runs at 3Mb wire speed with an effective throughput rate of
2.1Mb/s. All of the other platforms in AOSP set the UART speed to
3Mb/s.
The A64 hardware supports running the UART at 3Mb/s. This device tree
change will do that:
apb2 {
#clock-cells = <0x00>;
compatible = "allwinner,sunxi-periph-clock";
clock-output-names = "apb2";
assigned-clock-parents = <0x7b>; -- change the parent to
periph0x2 instead of OSC24
linux,phandle = <0x7e>;
phandle = <0x7e>;
};
But... doing that kills the console. The console's UART clock was
calculated for a 24Mhz input clock. When you change the clock parent
over to 1.2Ghz the console dies. So.... this parent switch needs to be
done in uboot, not Linux.
Can anyone help out with a uboot that changes this clock parent over
to periph0x2?
--
Jon Smirl
[email protected]
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