[LinuxPPS] kernel does not see PPS on serial port

[Rodolfo Giometti]

On Fri, Mar 07, 2008 at 10:14:28PM +1100, Cirilo Bernardo wrote:
> 
> Aside from what Rodolfo said about it being strange that no driver is
> shown for IRQ4,  I also noticed that IRQs are being assigned to
> different CPUs. Can you check with the older kernel if a driver is
> assigned and if IRQs are assigned to multiple CPUs or only to one of
> them?  I imagined there was a configuration for  CPU affinity of
> interrupt processing routines, but I can't find it or any references
> to it - I must be going senile.

This should not be a problem for PPS since the PPS events are
registered into the IRQ handler. No matter which CPU executes it.

> Does the order of loading modules matter?  For example, if 'pps' needs
> to load before the 8250 serial driver, then interesting things can
> happen when the serial driver is compiled into the kernel but the pps
> driver loads later.  I think there is a mechanism to ensure that the
> module is loaded and initialized before the inbuilt driver is
> initialized, so even if you have that strange case it should be
> possible to fix it.

This is not possible you cannot compile PPS as a module and the serial
support as built-in. See the file linux/drivers/pps/clients/Kconfig:

comment "UART serial support (forced off)"
	depends on ! (SERIAL_CORE != n && !(PPS = m && SERIAL_CORE = y))

config PPS_CLIENT_UART
	bool "UART serial support"
	depends on SERIAL_CORE != n && !(PPS = m && SERIAL_CORE = y)
	help
	  If you say yes here you get support for a PPS source connected
	  with the CD (Carrier Detect) pin of your serial port.

Also, when you do modprobe the system loads automagically al module
dependencies.

Ciao,

Rodolfo

-- 

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