Re: Sony Ericsson GC85 GPRS/EDGE pcmcia card

On Tue, Mar 29, 2005 at 01:39:05AM -0700, M. Warner Losh wrote:
> Let me rephrase: Your machine is too slow at servicing the
> interrupts.  Otherwise you wouldn't get an sio overflow.  Lowering the
> interrupt threshold can deal with this problem, since it increases the
> amount of latency that your machine will have.  This is 4.x, so you
> should still see decent interrupt latency, even with non-fast
> interrupts.  This doesn't match my expectations, since I've run the
> non-fast interrupts at 38400 before on 4.x, and I'd expect that
> something else is going on.  Either you aren't getting them, or the
> device looks like a 16550 because that's all we've enabled in its
> fifo, and the wireless data rates are much higher and need something
> special done with them.

Ok, I've reinstalled FreeBSD 4. The device appear like a 16550A in the
log:

sio4 at port 0x2e8-0x2ef irq 7 flags 0x40000 slot 1 on pccard1
sio4: type 16550A

> Getting sio overflows means that packet checksums should fail and
> retransmission should happen.  If you get only a few, it should still
> work.  chances are good that simpler, less bursty/chatty protocols
> work better, which is what you are seeing.

Ok.

> On second thought you may benefit from using isa interrupts.
> hw.pcic_intr_path=1 will allow you to assign interrupts via
> pccard.conf.  This may or may not help.  If it doesn't, make sure you
> are actually getting the interrupt (vmstat -i).

Now that worked. Setting hw.pcic.intr_path=1 let me force the sio-device
to irq 7. All messages are now gone, but the card still seems to have
problems. The "unable to activate interrupt in fast mode - using normal
mode" is gone, and I can't get any more sio overflows in the systemlog.

vmstat -i shows that sio4 irq7 is getting a lot of interrupts.

Could it be that it is in a conflict with other hardware on the system?
I know that the paralell port may use irq7. I have disabled it in my
kernel config, though.

> Do you know if your card is actually respecting the baud rate set, or
> just sending it as fast as it can?  What data rates does the device
> handle?

I have no idea. The card should support higher data rates than 115200,
because EDGE can go up to 238kbps (almost 3G). In Windows the card is
also a com port, but the highest posible baud rate is 115200. I guess
you need a little more to achieve 238kbps.

> 		com->fifo_image = com->unit == siotsunit ? 0
> 				  : t->c_ispeed <= 4800
> 				  ? FIFO_ENABLE : FIFO_ENABLE | FIFO_RX_MEDH;
> 
> You might change this to be FIFO_ENABLE, which will give you more
> interrupts, but a greater interrupt tolerenace.  You should also
> investigating to see if the card has a larger fifo that can be enabled
> (because it really is a 16650 or 16950 or the like).  This may help
> quite a bit if the card emulates something with a much larger fifo.

I done that too. The log entries may gave disappeared because of that,
not the hard setting of irq7 via hw.pcic.intr_path and pcmcia.conf.
Maybe I should try them one at a time, I think I got too optimistic here
:)

But still I have the same problem.

> Are you sure you are even getting interrupts for the sio card?  vmstat
> -i will tell you.  Otherwise, sio is falling back into polling mode,
> which works OK for slow data speeds, be terrible at high data rate.

Yes, it is getting interrupts according to the output of vmstat -i, at
irq7. I have also now tried to connect with the port set to both 115200
and 38400. But the result is the same.... :(

> Right now, I'd concentrate on understanding why 4.x fails.  I've run
> non-fast interrupts there as fast as 38400 w/o lost data on a 4.x
> laptop.  5.x's interrupt preformance might not be as good as 4.x's, so
> we should try to track down why interrupt latency is hurting you so
> much more than it hurts others.

That's ok. As I said I reinstalled FreeBSD 4 now, so we can try solving
it there first. I've also tried running at 38400, see above.

regards,

Espen
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