irq share problem
Here's a problem I already posted once, but stubornly remains:
I have 4 serial ports. 2 on board and 2 in an old i/o adapter.
The thing is that I cant have thenm both working at the same time.
I know waht you r thinkg " use different irqs". I cant, I have none left.
Both ports work very nice, if there's only one (of them) receiving.
The things I want to know are: Is there a way to configure the module
serial.o to handle this problem? ofcourse assuming that this is NOT
hardware matter. I am very confused because of this. According to some
things I have read, if the uart tries to notify the interrupt handler,
it will put 5V in the interrupt handler. Well, from the hardware " stand
point", having 2 ports working one at a time, is the same having both
working at the same time. I mean, If port1 wants to interrupt the cpu, it
will put 5V in the int3. If port 3 is not trying to interrupt the cpu, it
will put 0V, it works. Okay; Now if we reverse, port3 wants to interrupt
5V, and ports 1 puts0V the thing still works . But having two programs
read from port1 and from port3 ( one program per port) just doens work.
The only way this gives some output is when a simultaneous interrupts
occurs on both ports.
Can any one tell me how this may be solved? ( without probing each port?
that looses bytes ). Because I really hate to buy hardware I cant fully
serial.o reports IRQ_SHARE flag at boot up