[LinuxPPS] kernel does not see PPS on serial port

[LICHTENBERGER Janos]

>
> Do you mean you booted your new computer with the older kernel to
> check that PPS works and it does work?
>


Yes, I used the very same hardware, only the disk order was swapped in BIOS


> Rodolfo suggested the "cat /dev/ttyS0" because the serial port drivers
> are designed to disable the UART interrupts unless someone opens the
> device for communication.  This makes sense for the usual case -
> unless you are expecting data, why even watch the serial port.  The
> result of course is that you will not get the DCD interrupt unless you
> open the serial port - even if you never actually use the serial port
> data.
>

I did 'cat /dev/ttyS0' a few times, the irq 4 counter increased each time
after cat-ing, but otherwise remained unchanged


> I'm asking if you used the older kernel on the same hardware because
> some hardware only implements the Rx/Tx lines and not the DCD and
> other lines, so if you tested on two different machines then that is
> not a valid test.

No, in this case all the hardware was the same, I used two bootable disks
with old and new kernel

>
> Another problem I encounter is that the 8250 driver in particular
> tries to work around faults in numerous UART hardware which claims to
> be compatible with the old 8250.  Sometimes hardware is not identified
> correctly and the wrong driver is loaded.  In such a case, you can see
> what driver is associated with your serial port in your old kernel and
> in your new kernel.
>
> Yet another problem I encounter is with power management features on
> some boards and in some BIOSes.  Recently I found that with one board
> I have, I need to check the BIOS settings and turn off the "power
> management features active on boot" feature.  If it is active, then
> some peripherals are shut down on boot and Linux does not realize this
> or have any obvious mechanism for turning these peripherals on.  Well,
> maybe it is possible to turn on via the ACPI or APM interface, but for
> my purpose I don't even see the point in disabling these peripherals.
>


-- 
-- 
Dr. János Lichtenberger
Space Research Group,
Eötvös University,
Budapest, Pf 32 H-1518 Hungary
Tel: +36-1-372 2934
Fax: +36-1-372 2927