Re: eisa_set_level_irq(acpi_fadt.sci_int)

[Len Brown <len.brown-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

Actually that change in -pre8 was a no-op -- we still force the PIC
SCI from Edge to Level, just that now we print a message when we do so.

I expect the regression related to your lid switch is cased
by something else.  But since you have a box with an Edge Triggered
SCI, I'd be interested if you are able to receive ACPI interrupts
if we leave the SCI in Edge Triggered mode:

===== arch/i386/kernel/acpi.c 1.14 vs edited =====
--- 1.14/arch/i386/kernel/acpi.c        Mon Oct 20 18:08:05 2003
+++ edited/arch/i386/kernel/acpi.c      Thu Oct 23 23:09:05 2003
@@ -492,6 +492,8 @@
        if (!(val & mask)) {
                printk(KERN_WARNING PREFIX "IRQ %d was Edge Triggered, "
                        "setting to Level Triggerd\n", irq);
+               printk(KERN_WARNING PREFIX "NOT!\n");
+               return;
                outb(val | mask, port);
        }
 }

If you get a chance to try it, please send the /proc/interrupts
from before & after.

thanks,
-Len


On Thu, 2003-10-23 at 22:54, Sérgio Monteiro Basto wrote:
> Hi
> Seems that patch has been applied into kernel-2.4.23-pre8 and hangs my
> laptop when lid button is pressed.
> Here is dmesg file.
> where you can see ACPI: IRQ 10 was Edge Triggered, setting to Level
> Triggerd
> Notes: 
> With pre7 all works fine.
> I have APIC disable.
> Other buttons like sleep, power have the normal beaver 
> if I can help testing something else tell me.
> 
> thanks
> 
> On Wed, 2003-10-22 at 05:25, Len Brown wrote:
> > Ducrot,
> > I've found at least 1 system where hardcoding the PIC SCI to
> > Level-Triggered fails, while leaving it as Edge Triggered succeeds.
> > 
> > The Intel SE7505VB2 "Vero Beach" when booted with "noapic" leaves IRQ9
> > as edge triggered.
> > 
> > When we force it to level triggered, we get no ACPI events.
> > If we leave it as edge triggered, we do get ACPI events.
> > 
> > The other systems in my office leave the PIC SCI in Level Triggered
> > mode, so Linux need do nothing to the trigger.
> > 
> > Today's patch prints a warning when the mode changes:
> > 
> >                 printk(KERN_WARNING PREFIX "IRQ %d was Edge Triggered, "
> >                         "setting to Level Triggerd\n", irq);
> > 
> > But I'm thinking that by default we should _not_ change the trigger.
> > Instead we should do so only upon, say acpi=sci_level_trigger or some
> > such.  If there is a popular model that leaves SCI as edge and requires
> > level to work, then we can use DMI to set this param for it.
> > 
> > thanks,
> > -Len
> > 
> > On Fri, 2003-10-17 at 13:28, Len Brown wrote:
> > > On Fri, 2003-10-17 at 11:41, Ducrot Bruno wrote:
> > > > On Wed, Oct 15, 2003 at 05:48:04PM -0400, Len Brown wrote:
> > > > > What does eisa_set_level_irq() do for us?
> > > > > 
> > > > > As its presence breaks the !CONFIG_PCI build, I deleted it and found
> > > > > that ACPI in PIC mode seems to work just fine without it (at least on 2
> > > > > of 2 systems tested so far)
> > > > > 
> > > > 
> > > > This ensure SCI interrupt is correctly initialized for (poorly) written
> > > > BIOS.  Without it, this break one of my laptop, and certainly others as well.
> > > 
> > > Do ACPI interrupt work on this latop?  What happens on that system if
> > > you delete the call to eisa_set_level_irq()?
> > > 
> > > If we blindly program the PIC to be level senstive when the hardware is
> > > designed to be edge triggered, then we'll probably get no ACPI events on
> > > those systems, as the pulse may not be asserted long enough to provoke
> > > an interrupt.
> > > 
> > > We used to blindly program the APIC assuming the SCI was ACPI compliant,
> > > but we got burnt when we discovered that a significant set of system do
> > > _not_ have a level-triggered active-low SCI.  Most of those specified
> > > their deviation with an SCI-over-ride in the MADT, but some did not:
> > > http://bugzilla.kernel.org/show_bug.cgi?id=774
> > > 
> > > The APIC solution was to
> > > 1. don't hard-code level-triggered active-low
> > > 2. do whatever the SCI over-ride says
> > > 3. if no SCI over-ride, leave the interrupt trigger/polarity as the BIOS
> > > programmed it.
> > > 
> > > thanks,
> > > -Len
> > > 
> > > ps. this routine is mis-named, it it not EISA specific.  Further, it is
> > > mis-located in a PCI-specific file but is not PCI specific.  It should
> > > be in an X86 specific interrupt file and be named pic_something.  I'm
> > > thinking I'll clone it into our x86 acpi code and add a warning when we
> > > find that it actually _changes_ the polarity.



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