4 files changed, 46 insertions, 26 deletions

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 215443c378cc..a18218ccac1e 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -4422,10 +4422,10 @@
 #define   AUDIO_CP_READY_C		(1<<9)
 
 /* HSW Power Wells */
-#define HSW_PWR_WELL_CTL1			0x45400 /* BIOS */
-#define HSW_PWR_WELL_CTL2			0x45404 /* Driver */
-#define HSW_PWR_WELL_CTL3			0x45408 /* KVMR */
-#define HSW_PWR_WELL_CTL4			0x4540C /* Debug */
+#define HSW_PWR_WELL_BIOS			0x45400 /* CTL1 */
+#define HSW_PWR_WELL_DRIVER			0x45404 /* CTL2 */
+#define HSW_PWR_WELL_KVMR			0x45408 /* CTL3 */
+#define HSW_PWR_WELL_DEBUG			0x4540C /* CTL4 */
 #define   HSW_PWR_WELL_ENABLE			(1<<31)
 #define   HSW_PWR_WELL_STATE			(1<<30)
 #define HSW_PWR_WELL_CTL5			0x45410
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index c5997d260172..19ab75f307e5 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -8659,10 +8659,7 @@ static void i915_disable_vga(struct drm_device *dev)
 
 void intel_modeset_init_hw(struct drm_device *dev)
 {
-	/* We attempt to init the necessary power wells early in the initialization
-	 * time, so the subsystems that expect power to be enabled can work.
-	 */
-	intel_init_power_wells(dev);
+	intel_init_power_well(dev);
 
 	intel_prepare_ddi(dev);
 
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 66619d80348f..32c30423eaca 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -667,7 +667,7 @@ extern void intel_update_fbc(struct drm_device *dev);
 extern void intel_gpu_ips_init(struct drm_i915_private *dev_priv);
 extern void intel_gpu_ips_teardown(void);
 
-extern void intel_init_power_wells(struct drm_device *dev);
+extern void intel_init_power_well(struct drm_device *dev);
 extern void intel_enable_gt_powersave(struct drm_device *dev);
 extern void intel_disable_gt_powersave(struct drm_device *dev);
 extern void gen6_gt_check_fifodbg(struct drm_i915_private *dev_priv);
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 5a8a72c5a89d..b8cf16c06b1b 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4043,33 +4043,56 @@ void intel_init_clock_gating(struct drm_device *dev)
 	dev_priv->display.init_clock_gating(dev);
 }
 
-/* Starting with Haswell, we have different power wells for
- * different parts of the GPU. This attempts to enable them all.
+static void intel_set_power_well(struct drm_device *dev, bool enable)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	bool is_enabled, enable_requested;
+	uint32_t tmp;
+
+	tmp = I915_READ(HSW_PWR_WELL_DRIVER);
+	is_enabled = tmp & HSW_PWR_WELL_STATE;
+	enable_requested = tmp & HSW_PWR_WELL_ENABLE;
+
+	if (enable) {
+		if (!enable_requested)
+			I915_WRITE(HSW_PWR_WELL_DRIVER, HSW_PWR_WELL_ENABLE);
+
+		if (!is_enabled) {
+			DRM_DEBUG_KMS("Enabling power well\n");
+			if (wait_for((I915_READ(HSW_PWR_WELL_DRIVER) &
+				      HSW_PWR_WELL_STATE), 20))
+				DRM_ERROR("Timeout enabling power well\n");
+		}
+	} else {
+		if (enable_requested) {
+			I915_WRITE(HSW_PWR_WELL_DRIVER, 0);
+			DRM_DEBUG_KMS("Requesting to disable the power well\n");
+		}
+	}
+}
+
+/*
+ * Starting with Haswell, we have a "Power Down Well" that can be turned off
+ * when not needed anymore. We have 4 registers that can request the power well
+ * to be enabled, and it will only be disabled if none of the registers is
+ * requesting it to be enabled.
  */
-void intel_init_power_wells(struct drm_device *dev)
+void intel_init_power_well(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	unsigned long power_wells[] = {
-		HSW_PWR_WELL_CTL1,
-		HSW_PWR_WELL_CTL2,
-		HSW_PWR_WELL_CTL4
-	};
-	int i;
 
 	if (!IS_HASWELL(dev))
 		return;
 
 	mutex_lock(&dev->struct_mutex);
 
-	for (i = 0; i < ARRAY_SIZE(power_wells); i++) {
-		int well = I915_READ(power_wells[i]);
+	/* For now, we need the power well to be always enabled. */
+	intel_set_power_well(dev, true);
 
-		if ((well & HSW_PWR_WELL_STATE) == 0) {
-			I915_WRITE(power_wells[i], well & HSW_PWR_WELL_ENABLE);
-			if (wait_for((I915_READ(power_wells[i]) & HSW_PWR_WELL_STATE), 20))
-				DRM_ERROR("Error enabling power well %lx\n", power_wells[i]);
-		}
-	}
+	/* We're taking over the BIOS, so clear any requests made by it since
+	 * the driver is in charge now. */
+	if (I915_READ(HSW_PWR_WELL_BIOS) & HSW_PWR_WELL_ENABLE)
+		I915_WRITE(HSW_PWR_WELL_BIOS, 0);
 
 	mutex_unlock(&dev->struct_mutex);
 }