drm/i915/skl: enable PC9/10 power states during suspend-to-idle

During suspend-to-idle we need to keep the DMC firmware active and DC6
enabled, since otherwise we won't reach deep system power states like
PC9/10. The lead for this came from Nivedita who noticed that the
kernel's turbostat tool didn't report any PC9/10 residency change
across an 'echo freeze > /sys/power/state'.

Reported-by: Nivedita Swaminathan <nivedita.swaminathan@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1447860750-18110-1-git-send-email-imre.deak@intel.com

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 6344dfb..649e20a 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -624,6 +624,14 @@ static int vlv_resume_prepare(struct drm_i915_private *dev_priv,
                              bool rpm_resume);
 static int bxt_resume_prepare(struct drm_i915_private *dev_priv);
 
+static bool suspend_to_idle(struct drm_i915_private *dev_priv)
+{
+#if IS_ENABLED(CONFIG_ACPI_SLEEP)
+       if (acpi_target_system_state() < ACPI_STATE_S3)
+               return true;
+#endif
+       return false;
+}
 
 static int i915_drm_suspend(struct drm_device *dev)
 {
@@ -676,11 +684,7 @@ static int i915_drm_suspend(struct drm_device *dev)
 
        i915_save_state(dev);
 
-       opregion_target_state = PCI_D3cold;
-#if IS_ENABLED(CONFIG_ACPI_SLEEP)
-       if (acpi_target_system_state() < ACPI_STATE_S3)
-               opregion_target_state = PCI_D1;
-#endif
+       opregion_target_state = suspend_to_idle(dev_priv) ? PCI_D1 : PCI_D3cold;
        intel_opregion_notify_adapter(dev, opregion_target_state);
 
        intel_uncore_forcewake_reset(dev, false);
@@ -701,15 +705,26 @@ static int i915_drm_suspend(struct drm_device *dev)
 static int i915_drm_suspend_late(struct drm_device *drm_dev, bool hibernation)
 {
        struct drm_i915_private *dev_priv = drm_dev->dev_private;
+       bool fw_csr;
        int ret;
 
-       intel_power_domains_suspend(dev_priv);
+       fw_csr = suspend_to_idle(dev_priv) && dev_priv->csr.dmc_payload;
+       /*
+        * In case of firmware assisted context save/restore don't manually
+        * deinit the power domains. This also means the CSR/DMC firmware will
+        * stay active, it will power down any HW resources as required and
+        * also enable deeper system power states that would be blocked if the
+        * firmware was inactive.
+        */
+       if (!fw_csr)
+               intel_power_domains_suspend(dev_priv);
 
        ret = intel_suspend_complete(dev_priv);
 
        if (ret) {
                DRM_ERROR("Suspend complete failed: %d\n", ret);
-               intel_power_domains_init_hw(dev_priv, true);
+               if (!fw_csr)
+                       intel_power_domains_init_hw(dev_priv, true);
 
                return ret;
        }
@@ -730,6 +745,8 @@ static int i915_drm_suspend_late(struct drm_device *drm_dev, bool hibernation)
        if (!(hibernation && INTEL_INFO(dev_priv)->gen < 6))
                pci_set_power_state(drm_dev->pdev, PCI_D3hot);
 
+       dev_priv->suspended_to_idle = suspend_to_idle(dev_priv);
+
        return 0;
 }
 
@@ -842,8 +859,10 @@ static int i915_drm_resume_early(struct drm_device *dev)
         * FIXME: This should be solved with a special hdmi sink device or
         * similar so that power domains can be employed.
         */
-       if (pci_enable_device(dev->pdev))
-               return -EIO;
+       if (pci_enable_device(dev->pdev)) {
+               ret = -EIO;
+               goto out;
+       }
 
        pci_set_master(dev->pdev);
 
@@ -861,7 +880,12 @@ static int i915_drm_resume_early(struct drm_device *dev)
                hsw_disable_pc8(dev_priv);
 
        intel_uncore_sanitize(dev);
-       intel_power_domains_init_hw(dev_priv, true);
+
+       if (!(dev_priv->suspended_to_idle && dev_priv->csr.dmc_payload))
+               intel_power_domains_init_hw(dev_priv, true);
+
+out:
+       dev_priv->suspended_to_idle = false;
 
        return ret;
 }

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 5a5c06b..3d8741e 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1885,6 +1885,7 @@ struct drm_i915_private {
        u32 chv_phy_control;
 
        u32 suspend_count;
+       bool suspended_to_idle;
        struct i915_suspend_saved_registers regfile;
        struct vlv_s0ix_state vlv_s0ix_state;