[RFC 3/6] drm/i915: add enable_runtime_pm option

[Paulo Zanoni <przanoni@gmail.com>]

From: Paulo Zanoni <paulo.r.zanoni@intel.com>

And leave it off by default. We have way too many driver entry points,
we can't assume this will work without regressions without tons of
testing first. This option allows people to test and fix the problems.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
---
 drivers/gpu/drm/i915/i915_dma.c | 4 ++--
 drivers/gpu/drm/i915/i915_drv.c | 8 ++++++--
 drivers/gpu/drm/i915/i915_drv.h | 1 +
 drivers/gpu/drm/i915/intel_pm.c | 4 ++--
 4 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 6aa044e..dd4f424 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1458,7 +1458,7 @@ static void i915_init_runtime_pm(struct drm_i915_private *dev_priv)
 
 	dev_priv->pm.suspended = false;
 
-	if (!HAS_RUNTIME_PM(dev))
+	if (!HAS_RUNTIME_PM(dev) || !i915_enable_runtime_pm)
 		return;
 
 	pm_runtime_set_active(device);
@@ -1475,7 +1475,7 @@ static void i915_fini_runtime_pm(struct drm_i915_private *dev_priv)
 	struct drm_device *dev = dev_priv->dev;
 	struct device *device = &dev->pdev->dev;
 
-	if (!HAS_RUNTIME_PM(dev))
+	if (!HAS_RUNTIME_PM(dev) || !i915_enable_runtime_pm)
 		return;
 
 	/* Make sure we're not suspended first. */
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index a999a3f..c75b78f 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -154,6 +154,10 @@ module_param_named(prefault_disable, i915_prefault_disable, bool, 0600);
 MODULE_PARM_DESC(prefault_disable,
 		"Disable page prefaulting for pread/pwrite/reloc (default:false). For developers only.");
 
+int i915_enable_runtime_pm __read_mostly = 0;
+module_param_named(enable_runtime_pm, i915_enable_runtime_pm, int, 0600);
+MODULE_PARM_DESC(enable_runtime_pm, "Enable runtime PM on supported platforms (default: disabled)");
+
 static struct drm_driver driver;
 extern int intel_agp_enabled;
 
@@ -890,7 +894,7 @@ static int i915_runtime_suspend(struct device *device)
 	struct drm_device *dev = pci_get_drvdata(pdev);
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
-	WARN_ON(!HAS_RUNTIME_PM(dev));
+	WARN_ON(!HAS_RUNTIME_PM(dev) || !i915_enable_runtime_pm);
 
 	DRM_DEBUG_KMS("Suspending device\n");
 
@@ -909,7 +913,7 @@ static int i915_runtime_resume(struct device *device)
 	struct drm_device *dev = pci_get_drvdata(pdev);
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
-	WARN_ON(!HAS_RUNTIME_PM(dev));
+	WARN_ON(!HAS_RUNTIME_PM(dev) || !i915_enable_runtime_pm);
 
 	DRM_DEBUG_KMS("Resuming device\n");
 
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 74f2b5d..73ebb9e 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1831,6 +1831,7 @@ extern bool i915_fastboot __read_mostly;
 extern int i915_enable_pc8 __read_mostly;
 extern int i915_pc8_timeout __read_mostly;
 extern bool i915_prefault_disable __read_mostly;
+extern int i915_enable_runtime_pm __read_mostly;
 
 extern int i915_suspend(struct drm_device *dev, pm_message_t state);
 extern int i915_resume(struct drm_device *dev);
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index a973f35..617e934 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5785,7 +5785,7 @@ void intel_runtime_pm_get(struct drm_i915_private *dev_priv)
 	struct drm_device *dev = dev_priv->dev;
 	struct device *device = &dev->pdev->dev;
 
-	if (!HAS_RUNTIME_PM(dev))
+	if (!HAS_RUNTIME_PM(dev) || !i915_enable_runtime_pm)
 		return;
 
 	pm_runtime_mark_last_busy(device);
@@ -5798,7 +5798,7 @@ void intel_runtime_pm_put(struct drm_i915_private *dev_priv)
 	struct drm_device *dev = dev_priv->dev;
 	struct device *device = &dev->pdev->dev;
 
-	if (!HAS_RUNTIME_PM(dev))
+	if (!HAS_RUNTIME_PM(dev) || !i915_enable_runtime_pm)
 		return;
 
 	pm_runtime_mark_last_busy(device);
-- 
1.8.3.1