🚀 go-pugleaf

Daryl Sayers <daryl@stonemicro.com.au> writes:


>I have 2 onboard 16550 serial ports that have been working great. I need
>to install a third port so I got a basic 8250 seial card and installed this
                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>card as COM1 I then moved the 2 onboard serial ports to COM2 and COM3.

[...]

>ttyS0 Testing (COM1 8250 serial card IRQ 4 at 3F8)
                                      ^^^^^
>ttyS1 Modem   (COM2 16550 onboard serial IRQ 3 at 2F8)
>ttyS2 Mouse   (COM3 16550 onboard serial IRQ 4 at 3E8)
                                          ^^^^^

[...]
>When sending data out the testing port (ttyS0) it is VERY slow but not
>corrupt. A single character is sent about every 10seconds. Too my
>amazement when I moved the mouse the data then got sent. It seems that
>when the mouse (ttyS2 Irq 4) generates an interupt the service routine
>also checks the Transmit buffer of ttyS0 also at Irq 4.

And that's exactly what Linux is telling you.

>Reading the Serial Howto it seems I should be able to share interupts
>like this so what else have I missed. 

Read again. It explicitely states that you can NOT do this, unless
you're using a multiport card that knows how to share IRQs between several
devices, or do some soldering on the ISA bus yourself. The standard
PC's hardware architecture is broken where it comes to IRQ sharing
on the ISA bus.

>Even though the Linux probe finds the seial ports correctly I still
>use setserial to make sure the ports are configured correctly.

Put the first serial port on an interrupt of its own.

Michael
-- 
   Michael Buchenrieder * mibu@scrum.muc.de / mibu@scrum.greenie.muc.de 
**************************************************************************
Portable, adj.:
                          Survives system reboot.