drm/i915, intel_ips: When i915 loads after IPS, make IPS relink to i915.

The IPS driver is designed to be able to run detached from i915 and
just not enable GPU turbo in that case, in order to avoid module
dependencies between the two drivers.  This means that we don't know
what the load order between the two is going to be, and we had
previously only supported IPS after (optionally) i915, but not i915
after IPS.  If the wrong order was chosen, you'd get no GPU turbo, and
something like half the possible graphics performance.
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org

drivers/gpu/drm/i915/i915_dma.c

@@ -34,6 +34,7 @@
 #include "i915_drm.h"
 #include "i915_drv.h"
 #include "i915_trace.h"
+#include "../../../platform/x86/intel_ips.h"
 #include <linux/pci.h>
 #include <linux/vgaarb.h>
 #include <linux/acpi.h>
@@ -1870,6 +1871,26 @@ bool i915_gpu_turbo_disable(void)
 }
 EXPORT_SYMBOL_GPL(i915_gpu_turbo_disable);
 
+/**
+ * Tells the intel_ips driver that the i915 driver is now loaded, if
+ * IPS got loaded first.
+ *
+ * This awkward dance is so that neither module has to depend on the
+ * other in order for IPS to do the appropriate communication of
+ * GPU turbo limits to i915.
+ */
+static void
+ips_ping_for_i915_load(void)
+{
+	void (*link)(void);
+
+	link = symbol_get(ips_link_to_i915_driver);
+	if (link) {
+		link();
+		symbol_put(ips_link_to_i915_driver);
+	}
+}
+
 /**
  * i915_driver_load - setup chip and create an initial config
  * @dev: DRM device
@@ -2075,6 +2096,8 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 	dev_priv->mchdev_lock = &mchdev_lock;
 	spin_unlock(&mchdev_lock);
 
+	ips_ping_for_i915_load();
+
 	return 0;
 
 out_workqueue_free:

drivers/platform/x86/intel_ips.c

@@ -75,6 +75,7 @@
 #include <drm/i915_drm.h>
 #include <asm/msr.h>
 #include <asm/processor.h>
+#include "intel_ips.h"
 
 #define PCI_DEVICE_ID_INTEL_THERMAL_SENSOR 0x3b32
 
@@ -245,6 +246,7 @@
 #define thm_writel(off, val) writel((val), ips->regmap + (off))
 
 static const int IPS_ADJUST_PERIOD = 5000; /* ms */
+static bool late_i915_load = false;
 
 /* For initial average collection */
 static const int IPS_SAMPLE_PERIOD = 200; /* ms */
@@ -339,6 +341,9 @@ struct ips_driver {
 	u64 orig_turbo_ratios;
 };
 
+static bool
+ips_gpu_turbo_enabled(struct ips_driver *ips);
+
 /**
  * ips_cpu_busy - is CPU busy?
  * @ips: IPS driver struct
@@ -517,7 +522,7 @@ static void ips_disable_cpu_turbo(struct ips_driver *ips)
  */
 static bool ips_gpu_busy(struct ips_driver *ips)
 {
-	if (!ips->gpu_turbo_enabled)
+	if (!ips_gpu_turbo_enabled(ips))
 		return false;
 
 	return ips->gpu_busy();
@@ -532,7 +537,7 @@ static bool ips_gpu_busy(struct ips_driver *ips)
  */
 static void ips_gpu_raise(struct ips_driver *ips)
 {
-	if (!ips->gpu_turbo_enabled)
+	if (!ips_gpu_turbo_enabled(ips))
 		return;
 
 	if (!ips->gpu_raise())
@@ -549,7 +554,7 @@ static void ips_gpu_raise(struct ips_driver *ips)
  */
 static void ips_gpu_lower(struct ips_driver *ips)
 {
-	if (!ips->gpu_turbo_enabled)
+	if (!ips_gpu_turbo_enabled(ips))
 		return;
 
 	if (!ips->gpu_lower())
@@ -1454,6 +1459,31 @@ static bool ips_get_i915_syms(struct ips_driver *ips)
 	return false;
 }
 
+static bool
+ips_gpu_turbo_enabled(struct ips_driver *ips)
+{
+	if (!ips->gpu_busy && late_i915_load) {
+		if (ips_get_i915_syms(ips)) {
+			dev_info(&ips->dev->dev,
+				 "i915 driver attached, reenabling gpu turbo\n");
+			ips->gpu_turbo_enabled = !(thm_readl(THM_HTS) & HTS_GTD_DIS);
+		}
+	}
+
+	return ips->gpu_turbo_enabled;
+}
+
+void
+ips_link_to_i915_driver()
+{
+	/* We can't cleanly get at the various ips_driver structs from
+	 * this caller (the i915 driver), so just set a flag saying
+	 * that it's time to try getting the symbols again.
+	 */
+	late_i915_load = true;
+}
+EXPORT_SYMBOL_GPL(ips_link_to_i915_driver);
+
 static DEFINE_PCI_DEVICE_TABLE(ips_id_table) = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL,
 		     PCI_DEVICE_ID_INTEL_THERMAL_SENSOR), },

drivers/platform/x86/intel_ips.h

+/*
+ * Copyright (c) 2010 Intel Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * The full GNU General Public License is included in this distribution in
+ * the file called "COPYING".
+ */
+
+void ips_link_to_i915_driver(void);