drm/i915/gen9: Fix runtime PM refcounting in case DMC firmware isn't loaded

While we disable runtime PM and with that display power well support if
the DMC firmware isn't loaded, we still want to disable power wells
during system suspend and driver unload. So drop/reacquire the
corresponding power refcount during suspend/resume and driver unloading.
This also means we have to check if DMC is not loaded and skip enabling
DC states in the power well code.

v2:
- Reuse intel_csr_ucode_suspend() in intel_csr_ucode_fini() instead of
  opencoding the former. (Chris)
- Add docbook comment to the public resume and suspend functions.

CC: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1460980101-14713-1-git-send-email-imre.deak@intel.com

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index 1242fb5d3301..0ed3ec862733 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -809,6 +809,9 @@ static void gen9_dc_off_power_well_enable(struct drm_i915_private *dev_priv,
 static void gen9_dc_off_power_well_disable(struct drm_i915_private *dev_priv,
                                            struct i915_power_well *power_well)
 {
+        if (!dev_priv->csr.dmc_payload)
+                return;
+
         if (dev_priv->csr.allowed_dc_mask & DC_STATE_EN_UPTO_DC6)
                 skl_enable_dc6(dev_priv);
         else if (dev_priv->csr.allowed_dc_mask & DC_STATE_EN_UPTO_DC5)