Odd-looking serial console prompt on RPI2

[Ian Lepore]

On Sat, 2017-03-04 at 22:24 +0530, Jayachandran C. wrote:
> On Thu, Mar 2, 2017 at 7:35 AM, Ian Lepore <ian at freebsd.org> wrote:
> > 
> > On Wed, 2017-03-01 at 18:01 -0800, Oleksandr Tymoshenko wrote:
> > > 
> > > Ian Lepore (ian at freebsd.org) wrote:
> > > > 
> > > > 
> > > > On Wed, 2017-03-01 at 16:03 -0800, bob prohaska wrote:
> > > > > 
> > > > > 
> > > > > On Wed, Mar 01, 2017 at 09:20:13PM +0100, Michael Tuexen
> > > > > wrote:
> > > > > > 
> > > > > > 
> > > > > > 
> > > > > > Interesting... Let us know what works and what doesn't...
> > > > > > 
> > > > > > Best regards
> > > > > > Michael
> > > > > > 
> > > > > As of FreeBSD 12.0-CURRENT (RPI2) #0 r314450: Wed Mar  1
> > > > > 14:48:26
> > > > > PST
> > > > > 2017
> > > > > the serial console is still corrupt (output truncated, input
> > > > > not
> > > > > echoed
> > > > > but treated like the enter key).  The serial console does
> > > > > seem to
> > > > > work
> > > > > with U-boot and loader, so I don't think it's the upstream
> > > > > hardware.
> > > > > 
> > > > > The HDMI console looks normal and USB keyboard input seems to
> > > > > work.
> > > > > 
> > > > > There have been several updates to /usr/src/sys/dev/uart and
> > > > > it
> > > > > looks
> > > > > as if kernel updates are still coming. Maybe the job simply
> > > > > isn't
> > > > > done yet.
> > > > > 
> > > > > bob
> > > > > 
> > > > It seems like this might be caused by r314318.  Can someone
> > > > having
> > > > this problem confirm if 314317 works and 314318 fails?
> > > Tested on my RPi2, 314317 - works, 314318 - broken
> > > 
> > CC'ing jchandra at .
> > 
> > I wonder if there is some bad interaction when the same uart is
> > used as
> > a console and a tty?
> I don't have a RPi3 setup to test now, I will look at the code again
> to see if
> I can find an issue.
> 
> Otherwise I will revert the change until we can find why the RPi UART
> breaks
> with these changes.
> 
> Thanks,
> JC.

The bugs should be fixed as of r314682.  It looks like the bugs have
long been in the pl011 driver, but were masked by having a fifo depth
of 1 byte -- it all sorta worked by accident previously.

-- Ian