ACPI: delete _GTS/_BFS support

_GTS and _BFS were added to the suspend/resume flow
in the ACPI 2.0 specification.

Linux dutifully implemented _GTS and _BFS.
We discovered that it was rarely seen in systems
in the field.  Further, some of those systems had
AML so bogus that it could never work -- proof that
no other operating system supports _GTS and _BFS.
So we made _GTS and _BFS optional via modparam,
and disabled them by default.

But we've had to complicate some code to keep
this support in the kernel, as these methods are defined
to be evaluated very close to sleep entry and exit.
Indeed, no other AML is ever evaluated with interrupts off.

We have submitted a proposal for _GTS and _BFS
to be officially removed from the ACPI specification
on the next revision.  Here we remove it from Linux.

Signed-off-by: Len Brown <len.brown@intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 9 insertions, 64 deletions

diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index 23a53c013f1..bd35e3c5e53 100644
--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -28,34 +28,6 @@
 #include "internal.h"
 #include "sleep.h"
 
-u8 wake_sleep_flags = ACPI_NO_OPTIONAL_METHODS;
-static unsigned int gts, bfs;
-static int set_param_wake_flag(const char *val, struct kernel_param *kp)
-{
-	int ret = param_set_int(val, kp);
-
-	if (ret)
-		return ret;
-
-	if (kp->arg == (const char *)&gts) {
-		if (gts)
-			wake_sleep_flags |= ACPI_EXECUTE_GTS;
-		else
-			wake_sleep_flags &= ~ACPI_EXECUTE_GTS;
-	}
-	if (kp->arg == (const char *)&bfs) {
-		if (bfs)
-			wake_sleep_flags |= ACPI_EXECUTE_BFS;
-		else
-			wake_sleep_flags &= ~ACPI_EXECUTE_BFS;
-	}
-	return ret;
-}
-module_param_call(gts, set_param_wake_flag, param_get_int, &gts, 0644);
-module_param_call(bfs, set_param_wake_flag, param_get_int, &bfs, 0644);
-MODULE_PARM_DESC(gts, "Enable evaluation of _GTS on suspend.");
-MODULE_PARM_DESC(bfs, "Enable evaluation of _BFS on resume".);
-
 static u8 sleep_states[ACPI_S_STATE_COUNT];
 static bool pwr_btn_event_pending;
 
@@ -305,7 +277,7 @@ static int acpi_suspend_enter(suspend_state_t pm_state)
 	switch (acpi_state) {
 	case ACPI_STATE_S1:
 		barrier();
-		status = acpi_enter_sleep_state(acpi_state, wake_sleep_flags);
+		status = acpi_enter_sleep_state(acpi_state);
 		break;
 
 	case ACPI_STATE_S3:
@@ -319,8 +291,8 @@ static int acpi_suspend_enter(suspend_state_t pm_state)
 	/* This violates the spec but is required for bug compatibility. */
 	acpi_write_bit_register(ACPI_BITREG_SCI_ENABLE, 1);
 
-	/* Reprogram control registers and execute _BFS */
-	acpi_leave_sleep_state_prep(acpi_state, wake_sleep_flags);
+	/* Reprogram control registers */
+	acpi_leave_sleep_state_prep(acpi_state);
 
 	/* ACPI 3.0 specs (P62) says that it's the responsibility
 	 * of the OSPM to clear the status bit [ implying that the
@@ -603,9 +575,9 @@ static int acpi_hibernation_enter(void)
 	ACPI_FLUSH_CPU_CACHE();
 
 	/* This shouldn't return.  If it returns, we have a problem */
-	status = acpi_enter_sleep_state(ACPI_STATE_S4, wake_sleep_flags);
-	/* Reprogram control registers and execute _BFS */
-	acpi_leave_sleep_state_prep(ACPI_STATE_S4, wake_sleep_flags);
+	status = acpi_enter_sleep_state(ACPI_STATE_S4);
+	/* Reprogram control registers */
+	acpi_leave_sleep_state_prep(ACPI_STATE_S4);
 
 	return ACPI_SUCCESS(status) ? 0 : -EFAULT;
 }
@@ -617,8 +589,8 @@ static void acpi_hibernation_leave(void)
 	 * enable it here.
 	 */
 	acpi_enable();
-	/* Reprogram control registers and execute _BFS */
-	acpi_leave_sleep_state_prep(ACPI_STATE_S4, wake_sleep_flags);
+	/* Reprogram control registers */
+	acpi_leave_sleep_state_prep(ACPI_STATE_S4);
 	/* Check the hardware signature */
 	if (facs && s4_hardware_signature != facs->hardware_signature) {
 		printk(KERN_EMERG "ACPI: Hardware changed while hibernated, "
@@ -876,33 +848,7 @@ static void acpi_power_off(void)
 	/* acpi_sleep_prepare(ACPI_STATE_S5) should have already been called */
 	printk(KERN_DEBUG "%s called\n", __func__);
 	local_irq_disable();
-	acpi_enter_sleep_state(ACPI_STATE_S5, wake_sleep_flags);
-}
-
-/*
- * ACPI 2.0 created the optional _GTS and _BFS,
- * but industry adoption has been neither rapid nor broad.
- *
- * Linux gets into trouble when it executes poorly validated
- * paths through the BIOS, so disable _GTS and _BFS by default,
- * but do speak up and offer the option to enable them.
- */
-static void __init acpi_gts_bfs_check(void)
-{
-	acpi_handle dummy;
-
-	if (ACPI_SUCCESS(acpi_get_handle(ACPI_ROOT_OBJECT, METHOD_PATHNAME__GTS, &dummy)))
-	{
-		printk(KERN_NOTICE PREFIX "BIOS offers _GTS\n");
-		printk(KERN_NOTICE PREFIX "If \"acpi.gts=1\" improves suspend, "
-			"please notify linux-acpi@vger.kernel.org\n");
-	}
-	if (ACPI_SUCCESS(acpi_get_handle(ACPI_ROOT_OBJECT, METHOD_PATHNAME__BFS, &dummy)))
-	{
-		printk(KERN_NOTICE PREFIX "BIOS offers _BFS\n");
-		printk(KERN_NOTICE PREFIX "If \"acpi.bfs=1\" improves resume, "
-			"please notify linux-acpi@vger.kernel.org\n");
-	}
+	acpi_enter_sleep_state(ACPI_STATE_S5);
 }
 
 int __init acpi_sleep_init(void)
@@ -963,6 +909,5 @@ int __init acpi_sleep_init(void)
 	 * object can also be evaluated when the system enters S5.
 	 */
 	register_reboot_notifier(&tts_notifier);
-	acpi_gts_bfs_check();
 	return 0;
 }