Re: suspend kills serial wacom tablet

[Bjorn Helgaas <bjorn.helgaas@hp.com>]

On Friday 13 April 2007 13:16, Dmitry Torokhov wrote:
> On 4/13/07, Bjorn Helgaas <bjorn.helgaas@hp.com> wrote:
> > On Tuesday 20 February 2007 06:52, marco wrote:
> > > I have a thinkpad X41-tablet which uses the linuxwacom serial drivers.
> > > The tablet works perfectly when the laptop first boots, but does not work
> > > at all after resuming from sleep.  I posted to the linuxwacom list but
> > > think that the problem might be more general in how acpi resumes the
> > > serial ports.
> > >
> > > As suggested here:
> > > http://www.thinkwiki.org/wiki/Installing_Ubuntu_6.10_on_a_ThinkPad_X41_Tablet
> > > I have added a script to resume.d which calls the setserial command:
> > >   /bin/setserial /dev/ttyS0 port 0x0200 irq 5 autoconfig
> >
> > Using setserial to change port or IRQ usage is a good clue that the
> > kernel is doing something wrong.  Usually it's "we KNOW that ttyS0
> > lives at 0x3f8 and IRQ 4, so we'll ignore what ACPI is telling us."
> > But it sounds like this is a tangent and not related to your current
> > problem.
> >
> > Can you post the dmesg log from a boot where the tablet works
> > correctly?  That will tell us exactly what kernel you're running
> > and how the kernel detected the serial port.  There've been some
> > serial port resume changes in the not-too-distant past, and I
> > don't know whether they're in the Ubuntu kernel yet.
> 
> It has nothing to do with changes to serial. Wacom driver for tablets
> connected to serial ports lives completely in userspace (X) and is
> completelyunaware that the box is coming out of sleep and that
> conncted device needs to be reinitialized.

OK, that sounds good, because if it's an X issue, it's Someone Else's
Problem :-)

I'm a little concerned because Marco said that after a resume,
"cat /dev/ttyS0" caused his system to hang, and not even Ctrl-Alt-Del
worked.  Can we blame that all on X?

Would stopping the X server before suspend and restarting
it after resume be a workaround?

Bjorn