From: Len Brown <len.brown@intel.com>
Date: Wed, 20 Jan 2010 04:10:04 +0000 (-0500)
Subject: ACPI: allow C3 > 1000usec
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=a6d72c189f6c4292ba1a323e8af24083790529f8;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

ACPI: allow C3 > 1000usec

Do for C3 what the previous patch did for C2.

The C2 patch was in response to a highly visible
and multiply reported C-state/turbo failure,
while this change has no bug report in-hand.

This will enable C3 in Linux on systems where BIOS
overstates C3 latency in _CST.  It will also enable
future systems which may actually have C3 > 1000usec.

Linux has always ignored ACPI BIOS C3 with exit latency > 1000 usec,
and the ACPI spec is clear that is correct FADT-supplied C3.

However, the ACPI spec explicitly states that _CST-supplied C-states
have no latency limits.

So move the 1000usec C3 test out of the code shared
by FADT and _CST code-paths, and into the FADT-specific path.

Signed-off-by: Len Brown <len.brown@intel.com>
---

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 8f6da9acc8e4..2c543b42eb1c 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -316,6 +316,17 @@ static int acpi_processor_get_power_info_fadt(struct acpi_processor *pr)
 		pr->power.states[ACPI_STATE_C2].address = 0;
 	}
 
+	/*
+	 * FADT supplied C3 latency must be less than or equal to
+	 * 1000 microseconds.
+	 */
+	if (acpi_gbl_FADT.C3latency > ACPI_PROCESSOR_MAX_C3_LATENCY) {
+		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+			"C3 latency too large [%d]\n", acpi_gbl_FADT.C3latency));
+		/* invalidate C3 */
+		pr->power.states[ACPI_STATE_C3].address = 0;
+	}
+
 	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 			  "lvl2[0x%08x] lvl3[0x%08x]\n",
 			  pr->power.states[ACPI_STATE_C2].address,
@@ -532,16 +543,6 @@ static void acpi_processor_power_verify_c3(struct acpi_processor *pr,
 	if (!cx->address)
 		return;
 
-	/*
-	 * C3 latency must be less than or equal to 1000
-	 * microseconds.
-	 */
-	else if (cx->latency > ACPI_PROCESSOR_MAX_C3_LATENCY) {
-		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
-				  "latency too large [%d]\n", cx->latency));
-		return;
-	}
-
 	/*
 	 * PIIX4 Erratum #18: We don't support C3 when Type-F (fast)
 	 * DMA transfers are used by any ISA device to avoid livelock.