x86/irq: Remove sis apic bug workaround

[firefly-linux-kernel-4.4.55.git] / arch / x86 / kernel / apic / io_apic.c

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 4fb347f01653a48c746d8bfe16ac6905fbe1358b..9806f9605bc4a2c3c4c0a62600628be6912bdabd 100644 (file)
--- 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
- * lose 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;