Re: 2.4.22 APM problems with IBM Thinkpad's

[Mikael Pettersson]

Ruben Puettmann writes:
 > 
 >     hy,
 > 
 > cause many problems with acpi I try to get apm running on my ibm
 > thinkpad R40 ( 2722). But with 2.4.22-pre10 and 2.4.22-pre10-ac1.
 > 
 > Problems which happend:
 > 
 > apm -s don't work with radeonfb usb and so on see my mails on lkm the
 > last days
 > 
 > If CONFIG_APM_DISPLAY_BLANK is Y the thinkpad freezed on blanking the
 > display

This sounds like a well-known APM/local-APIC clash.

Never ever use DISPLAY_BLANK if you also have SMP or UP_APIC.

With APIC support enabled (SMP or UP_APIC), APM must be constrained:
DISPLAY_BLANK off
CPU_IDLE off
built-in driver, not module

This is because the apm driver does BIOS calls, and many BIOSen
(including the code in graphics cards, e.g. all Radeons it seems)
like to hang if a local APIC timer interrupt arrives.
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