[PATCH] i386: port ATI timer fix from x86_64 to i386 II

ATI chipsets tend to generate double timer interrupts for the local APIC
timer when both the 8254 and the IO-APIC timer pins are enabled.  This is
because they route it to both and the result is anded together and the CPU
ends up processing it twice.

This patch changes check_timer to disable the 8254 routing for interrupt 0.

I think it would be safe on all chipsets actually (i tested it on a couple
and it worked everywhere) and Windows seems to do it in a similar way, but
to be conservative this patch only enables this mode on ATI (and adds
options to enable/disable too)

Ported over from a similar x86-64 change.

I reused the ACPI earlyquirk infrastructure for the ATI bridge check, but
tweaked it a bit to work even without ACPI.

Inspired by a patch from Chuck Ebbert, but redone.

Cc: Chuck Ebbert <[email protected]>
Cc: "Brown, Len" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index bad5987c47279fbe8ab211026872e42eec0e0505..fc99075e0af47f0b73a2ae2dfb7d19920c604dea 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -335,6 +335,12 @@ running once the system is up.
                        timesource is not avalible, it defaults to PIT.
                        Format: { pit | tsc | cyclone | pmtmr }
 
+       disable_8254_timer
+       enable_8254_timer
+                       [IA32/X86_64] Disable/Enable interrupt 0 timer routing
+                       over the 8254 in addition to over the IO-APIC. The
+                       kernel tries to set a sensible default.
+
        hpet=           [IA-32,HPET] option to disable HPET and use PIT.
                        Format: disable
 

diff --git a/arch/i386/kernel/Makefile b/arch/i386/kernel/Makefile
index 53bb9a79e274e5cf685edf4ffaa89c840a5954bd..65656c033d70d6eb93dd4e9c080bd1151161cdd3 100644 (file)
--- a/arch/i386/kernel/Makefile
+++ b/arch/i386/kernel/Makefile
@@ -11,7 +11,7 @@ obj-y := process.o semaphore.o signal.o entry.o traps.o irq.o \
 
 obj-y                          += cpu/
 obj-y                          += timers/
-obj-$(CONFIG_ACPI)             += acpi/
+obj-y                          += acpi/
 obj-$(CONFIG_X86_BIOS_REBOOT)  += reboot.o
 obj-$(CONFIG_MCA)              += mca.o
 obj-$(CONFIG_X86_MSR)          += msr.o

diff --git a/arch/i386/kernel/acpi/Makefile b/arch/i386/kernel/acpi/Makefile
index d51c7313cae8ac621c69f4be28718142d12b370e..7e9ac99354f43212bbbb6aa959642b0ec7dce91c 100644 (file)
--- a/arch/i386/kernel/acpi/Makefile
+++ b/arch/i386/kernel/acpi/Makefile
@@ -1,4 +1,4 @@
-obj-y                          := boot.o
+obj-$(CONFIG_ACPI)             += boot.o
 obj-$(CONFIG_X86_IO_APIC)      += earlyquirk.o
 obj-$(CONFIG_ACPI_SLEEP)       += sleep.o wakeup.o
 

diff --git a/arch/i386/kernel/acpi/boot.c b/arch/i386/kernel/acpi/boot.c
index 79577f0ace98847ee39a4f7ad4c9842f3ea88ec6..f1a21945963d77b80f125db518a432580647f10a 100644 (file)
--- a/arch/i386/kernel/acpi/boot.c
+++ b/arch/i386/kernel/acpi/boot.c
@@ -1111,9 +1111,6 @@ int __init acpi_boot_table_init(void)
                disable_acpi();
                return error;
        }
-#ifdef __i386__
-       check_acpi_pci();
-#endif
 
        acpi_table_parse(ACPI_BOOT, acpi_parse_sbf);
 

diff --git a/arch/i386/kernel/acpi/earlyquirk.c b/arch/i386/kernel/acpi/earlyquirk.c
index f1b9d2a46dab860c0cbf100e1bf6b9b0b220c024..2e3b643a4dc4df57552562015349c7657ca5b5d6 100644 (file)
--- a/arch/i386/kernel/acpi/earlyquirk.c
+++ b/arch/i386/kernel/acpi/earlyquirk.c
@@ -7,14 +7,22 @@
 #include <linux/pci.h>
 #include <asm/pci-direct.h>
 #include <asm/acpi.h>
+#include <asm/apic.h>
 
 static int __init check_bridge(int vendor, int device)
 {
+#ifdef CONFIG_ACPI
        /* According to Nvidia all timer overrides are bogus. Just ignore
           them all. */
        if (vendor == PCI_VENDOR_ID_NVIDIA) {
                acpi_skip_timer_override = 1;
        }
+#endif
+       if (vendor == PCI_VENDOR_ID_ATI && timer_over_8254 == 1) {
+               timer_over_8254 = 0;
+               printk(KERN_INFO "ATI board detected. Disabling timer routing "
+                               "over 8254.\n");
+       }
        return 0;
 }
 

diff --git a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c
index 235822b3f41b1db6d8a758ec0c2abd4f9c0c6726..39d9a5fa907e2eb6d40f098fcac9bb6d1ce6b9ef 100644 (file)
--- a/arch/i386/kernel/io_apic.c
+++ b/arch/i386/kernel/io_apic.c
@@ -51,6 +51,8 @@ static struct { int pin, apic; } ioapic_i8259 = { -1, -1 };
 
 static DEFINE_SPINLOCK(ioapic_lock);
 
+int timer_over_8254 __initdata = 1;
+
 /*
  *     Is the SiS APIC rmw bug present ?
  *     -1 = don't know, 0 = no, 1 = yes
@@ -2267,7 +2269,8 @@ static inline void check_timer(void)
        apic_write_around(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_EXTINT);
        init_8259A(1);
        timer_ack = 1;
-       enable_8259A_irq(0);
+       if (timer_over_8254 > 0)
+               enable_8259A_irq(0);
 
        pin1  = find_isa_irq_pin(0, mp_INT);
        apic1 = find_isa_irq_apic(0, mp_INT);
@@ -2392,6 +2395,20 @@ void __init setup_IO_APIC(void)
                print_IO_APIC();
 }
 
+static int __init setup_disable_8254_timer(char *s)
+{
+       timer_over_8254 = -1;
+       return 1;
+}
+static int __init setup_enable_8254_timer(char *s)
+{
+       timer_over_8254 = 2;
+       return 1;
+}
+
+__setup("disable_8254_timer", setup_disable_8254_timer);
+__setup("enable_8254_timer", setup_enable_8254_timer);
+
 /*
  *     Called after all the initialization is done. If we didnt find any
  *     APIC bugs then we can allow the modify fast path

diff --git a/arch/i386/kernel/setup.c b/arch/i386/kernel/setup.c
index 51e513b4f72d02db2e5c2dcac9b09d905c9854ed..ab62a9f4701edd22c69910ae05b71edde14bdd99 100644 (file)
--- a/arch/i386/kernel/setup.c
+++ b/arch/i386/kernel/setup.c
@@ -1599,6 +1599,10 @@ void __init setup_arch(char **cmdline_p)
        if (efi_enabled)
                efi_map_memmap();
 
+#ifdef CONFIG_X86_IO_APIC
+       check_acpi_pci();       /* Checks more than just ACPI actually */
+#endif
+
 #ifdef CONFIG_ACPI
        /*
         * Parse the ACPI tables for possible boot-time SMP configuration.

diff --git a/include/asm-i386/apic.h b/include/asm-i386/apic.h
index d30b8571573fd7dcb87d225f287b746c85cbdd8f..ff9ac8d19eb2584565cb5d8f93b196dc929cbc2d 100644 (file)
--- a/include/asm-i386/apic.h
+++ b/include/asm-i386/apic.h
@@ -137,6 +137,8 @@ void switch_APIC_timer_to_ipi(void *cpumask);
 void switch_ipi_to_APIC_timer(void *cpumask);
 #define ARCH_APICTIMER_STOPS_ON_C3     1
 
+extern int timer_over_8254;
+
 #else /* !CONFIG_X86_LOCAL_APIC */
 static inline void lapic_shutdown(void) { }