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Subject[Patch Part2 v5 21/33] x86/irq: Remove sis apic bug workaround
Date
From: Thomas Gleixner <tglx@linutronix.de>

The SiS apic bug workaround is now obsolete as we cache the register
values for performance reasons.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
---
arch/x86/include/asm/io_apic.h | 3 ---
arch/x86/kernel/apic/io_apic.c | 35 ++++++++++-------------------------
drivers/pci/quirks.c | 7 -------
3 files changed, 10 insertions(+), 35 deletions(-)

diff --git a/arch/x86/include/asm/io_apic.h b/arch/x86/include/asm/io_apic.h
index 67bdb72caeaf..cca97c961641 100644
--- a/arch/x86/include/asm/io_apic.h
+++ b/arch/x86/include/asm/io_apic.h
@@ -120,9 +120,6 @@ extern int mp_irq_entries;
/* MP IRQ source entries */
extern struct mpc_intsrc mp_irqs[MAX_IRQ_SOURCES];

-/* Older SiS APIC requires we rewrite the index register */
-extern int sis_apic_bug;
-
/* 1 if "noapic" boot option passed */
extern int skip_ioapic_setup;

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index c06f4b531392..71971b89da59 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -18,6 +18,16 @@
* and Rolf G. Tews
* for testing these extensively
* Paul Diefenbaugh : Added full ACPI support
+ *
+ * Historical information which is worth to be preserved:
+ *
+ * - SiS APIC rmw bug:
+ *
+ * We used to have a workaround for a bug in SiS chips which
+ * required to rewrite the index register for a read-modify-write
+ * operation as the chip lost the index information which was
+ * setup for the read already. We cache the data now, so that
+ * workaround has been removed.
*/

#include <linux/mm.h>
@@ -66,17 +76,6 @@
#define for_each_irq_pin(entry, head) \
list_for_each_entry(entry, &head, list)

-/*
- * Is the SiS APIC rmw bug present ?
- * -1 = don't know, 0 = no, 1 = yes
- * When doing a read-modify-write operation on IOAPIC registers, older SiS APIC
- * requires we rewrite the index register again where the read already set up
- * the index register.
- * The code to make use of sis_apic_bug has been removed, but we don't want to
- * loss this knowledge.
- */
-int sis_apic_bug = -1;
-
static DEFINE_RAW_SPINLOCK(ioapic_lock);
static DEFINE_MUTEX(ioapic_mutex);
static unsigned int ioapic_dynirq_base;
@@ -2320,20 +2319,6 @@ void __init setup_IO_APIC(void)
ioapic_initialized = 1;
}

-/*
- * Called after all the initialization is done. If we didn't find any
- * APIC bugs then we can allow the modify fast path
- */
-
-static int __init io_apic_bug_finalize(void)
-{
- if (sis_apic_bug == -1)
- sis_apic_bug = 0;
- return 0;
-}
-
-late_initcall(io_apic_bug_finalize);
-
static void resume_ioapic_id(int ioapic_idx)
{
unsigned long flags;
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 85f247e28a80..d532b8ebf460 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -819,13 +819,6 @@ static void quirk_amd_ioapic(struct pci_dev *dev)
}
}
DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_VIPER_7410, quirk_amd_ioapic);
-
-static void quirk_ioapic_rmw(struct pci_dev *dev)
-{
- if (dev->devfn == 0 && dev->bus->number == 0)
- sis_apic_bug = 1;
-}
-DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_SI, PCI_ANY_ID, quirk_ioapic_rmw);
#endif /* CONFIG_X86_IO_APIC */

/*
--
1.7.10.4


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