On Fri, May 19, 2017 at 08:17:50PM +0200, Mark Kettenis wrote: > The "official" Firefly-RK3399 firmware use a baudrate of 1.5 Mbps. > This is somewhat annoying (OpenBSD/arm64 expects the console to run at > 115200 bps) and I plan to provide firmware images that use the > standard rate instead. But until I figure out how to properly build > ATF (ARM Trusted Firmware) for the board, I'm stuck with 1.5 MBps. > > The Firefly-RK3399 board that was donated to me came with a little > serial-to-USB converter board that containst a Silican Labs CP2104 > chip. This chip is supported by uslcom(4), but that drivers limits > the baudrate to speeds up to 921600. But the chip defenitely supports > the higher rates. > > Turns out the older CP2101/2/3 chips only support speeds up to 921600 > bps, but later chips support speeds up to 2 Mbps. The diff below > raises the limit to 2 Mbps. This allows me to connect to the board. > > I'm not sure what happens if you try to configure speeds above 921600 > for the older chips. My guess would be that the USLCOM_SET_BAUD_RATE > command will fail, but maybe it will simply pick a supported speed. I > don't think that's a big issue and it's not really worth trying to > figure out which of the supported devices don't support the high > rates, > > ok? > > > Index: uslcom.c > =================================================================== > RCS file: /cvs/src/sys/dev/usb/uslcom.c,v > retrieving revision 1.39 > diff -u -p -r1.39 uslcom.c > --- uslcom.c 2 Sep 2016 09:14:59 -0000 1.39 > +++ uslcom.c 19 May 2017 18:12:19 -0000 > @@ -438,7 +438,7 @@ uslcom_param(void *vsc, int portno, stru > uint32_t baudrate, flowctrl[4]; > int data; > > - if (t->c_ospeed <= 0 || t->c_ospeed > 921600) > + if (t->c_ospeed <= 0 || t->c_ospeed > 2000000) > return (EINVAL); > > baudrate = t->c_ospeed; >
Command doesn't fail on older chips though I doubt they actually run at 2000000 in the end. uslcom0 at uhub3 port 2 configuration 1 interface 0 "Silicon Labs CP2102 USB to UART Bridge Controller" rev 1.10/1.00 addr 5 ucom0 at uslcom0 portno 0 before: # cu -l cuaU0 -s 2000000 cu: tcsetattr: Invalid argument after: # cu -l cuaU0 -s 2000000 Connected to /dev/cuaU0 (speed 2000000) Anyway this is worth doing, perhaps add a note in uslcom(4) about which hardware can only do 921600 and which tops out at 2000000. ok jsg@ Attached a port that builds a rk3399 atf bl31.bin, no idea what it puts out on serial, perhaps that would require switching from release to debug.
arm-trusted-firmware.tgz
Description: application/tar-gz
