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x86: I/O APIC: timer through 8259A second-chance
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Some systems incorrectly report the ExtINTA pin of the I/O APIC as the
genuine target of the timer interrupt.  Here is a change that copies timer
pin information found to the other pin if one has been found only.  This
way both a direct and a through-8259A route is tested with the pin letting
these problematic systems work well enough.  If no timer pin information
has been found for the I/O APIC, then local APIC variations are tried
only, similarly to what is done without the change (except without the
misleading messages).

Obviously if we try the first-chance path without being told by the BIOS
to do so, we should not complain either, so do not print the message in
this case.

The 64-bit variation should be updated with a call to
replace_pin_at_irq() which can be done with the upcoming merge.  Since
add_pin_to_irq() is now always called in the first-chance path, the
condition to require it in the second-chance path no longer happens.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Maciej W. Rozycki authored and Ingo Molnar committed Jul 8, 2008
1 parent 03be750 commit 691874f
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Showing 2 changed files with 57 additions and 17 deletions.
38 changes: 28 additions & 10 deletions arch/x86/kernel/io_apic_32.c
View file
Expand Up @@ -2122,6 +2122,7 @@ static inline void __init unlock_ExtINT_logic(void)
static inline void __init check_timer(void)
{
int apic1, pin1, apic2, pin2;
int no_pin1 = 0;
int vector;
unsigned int ver;
unsigned long flags;
Expand Down Expand Up @@ -2159,10 +2160,30 @@ static inline void __init check_timer(void)
printk(KERN_INFO "..TIMER: vector=0x%02X apic1=%d pin1=%d apic2=%d pin2=%d\n",
vector, apic1, pin1, apic2, pin2);

/*
* Some BIOS writers are clueless and report the ExtINTA
* I/O APIC input from the cascaded 8259A as the timer
* interrupt input. So just in case, if only one pin
* was found above, try it both directly and through the
* 8259A.
*/
if (pin1 == -1) {
pin1 = pin2;
apic1 = apic2;
no_pin1 = 1;
} else if (pin2 == -1) {
pin2 = pin1;
apic2 = apic1;
}

if (pin1 != -1) {
/*
* Ok, does IRQ0 through the IOAPIC work?
*/
if (no_pin1) {
add_pin_to_irq(0, apic1, pin1);
setup_timer_IRQ0_pin(apic1, pin1, vector);
}
unmask_IO_APIC_irq(0);
if (timer_irq_works()) {
if (nmi_watchdog == NMI_IO_APIC) {
Expand All @@ -2174,26 +2195,23 @@ static inline void __init check_timer(void)
goto out;
}
clear_IO_APIC_pin(apic1, pin1);
printk(KERN_ERR "..MP-BIOS bug: 8254 timer not connected to "
"IO-APIC\n");
}
if (!no_pin1)
printk(KERN_ERR "..MP-BIOS bug: "
"8254 timer not connected to IO-APIC\n");

printk(KERN_INFO "...trying to set up timer (IRQ0) through the 8259A ... ");
if (pin2 != -1) {
printk(KERN_INFO "...trying to set up timer (IRQ0) "
"through the 8259A ... ");
printk("\n..... (found pin %d) ...", pin2);
/*
* legacy devices should be connected to IO APIC #0
*/
replace_pin_at_irq(0, apic1, pin1, apic2, pin2);
setup_timer_IRQ0_pin(apic2, pin2, vector);
unmask_IO_APIC_irq(0);
enable_8259A_irq(0);
if (timer_irq_works()) {
printk("works.\n");
timer_through_8259 = 1;
if (pin1 != -1)
replace_pin_at_irq(0, apic1, pin1, apic2, pin2);
else
add_pin_to_irq(0, apic2, pin2);
if (nmi_watchdog == NMI_IO_APIC) {
disable_8259A_irq(0);
setup_nmi();
Expand All @@ -2206,8 +2224,8 @@ static inline void __init check_timer(void)
*/
disable_8259A_irq(0);
clear_IO_APIC_pin(apic2, pin2);
printk(" failed.\n");
}
printk(" failed.\n");

if (nmi_watchdog == NMI_IO_APIC) {
printk(KERN_WARNING "timer doesn't work through the IO-APIC - disabling NMI Watchdog!\n");
Expand Down
36 changes: 29 additions & 7 deletions arch/x86/kernel/io_apic_64.c
View file
Expand Up @@ -1638,6 +1638,7 @@ static inline void __init check_timer(void)
struct irq_cfg *cfg = irq_cfg + 0;
int apic1, pin1, apic2, pin2;
unsigned long flags;
int no_pin1 = 0;

local_irq_save(flags);

Expand All @@ -1662,10 +1663,30 @@ static inline void __init check_timer(void)
apic_printk(APIC_VERBOSE,KERN_INFO "..TIMER: vector=0x%02X apic1=%d pin1=%d apic2=%d pin2=%d\n",
cfg->vector, apic1, pin1, apic2, pin2);

/*
* Some BIOS writers are clueless and report the ExtINTA
* I/O APIC input from the cascaded 8259A as the timer
* interrupt input. So just in case, if only one pin
* was found above, try it both directly and through the
* 8259A.
*/
if (pin1 == -1) {
pin1 = pin2;
apic1 = apic2;
no_pin1 = 1;
} else if (pin2 == -1) {
pin2 = pin1;
apic2 = apic1;
}

if (pin1 != -1) {
/*
* Ok, does IRQ0 through the IOAPIC work?
*/
if (no_pin1) {
add_pin_to_irq(0, apic1, pin1);
setup_timer_IRQ0_pin(apic1, pin1, vector);
}
unmask_IO_APIC_irq(0);
if (!no_timer_check && timer_irq_works()) {
nmi_watchdog_default();
Expand All @@ -1678,18 +1699,19 @@ static inline void __init check_timer(void)
goto out;
}
clear_IO_APIC_pin(apic1, pin1);
apic_printk(APIC_QUIET,KERN_ERR "..MP-BIOS bug: 8254 timer not "
"connected to IO-APIC\n");
}
if (!no_pin1)
apic_printk(APIC_QUIET,KERN_ERR "..MP-BIOS bug: "
"8254 timer not connected to IO-APIC\n");

apic_printk(APIC_VERBOSE,KERN_INFO "...trying to set up timer (IRQ0) "
"through the 8259A ... ");
if (pin2 != -1) {
apic_printk(APIC_VERBOSE,KERN_INFO
"...trying to set up timer (IRQ0) "
"through the 8259A ... ");
apic_printk(APIC_VERBOSE,"\n..... (found apic %d pin %d) ...",
apic2, pin2);
/*
* legacy devices should be connected to IO APIC #0
*/
/* replace_pin_at_irq(0, apic1, pin1, apic2, pin2); */
setup_timer_IRQ0_pin(apic2, pin2, cfg->vector);
unmask_IO_APIC_irq(0);
enable_8259A_irq(0);
Expand All @@ -1709,8 +1731,8 @@ static inline void __init check_timer(void)
*/
disable_8259A_irq(0);
clear_IO_APIC_pin(apic2, pin2);
apic_printk(APIC_VERBOSE," failed.\n");
}
apic_printk(APIC_VERBOSE," failed.\n");

if (nmi_watchdog == NMI_IO_APIC) {
printk(KERN_WARNING "timer doesn't work through the IO-APIC - disabling NMI Watchdog!\n");
Expand Down

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