drm/i915/hdmi: Ensure the HW is powered during HW state readout

The assumption when adding the intel_display_power_is_enabled() checks
was that if it returns success the power can't be turned off afterwards
during the HW access, which is guaranteed by modeset locks. This isn't
always true, so make sure we hold a dedicated reference for the time of
the access.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1455296121-4742-12-git-send-email-imre.deak@intel.com

diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index edb7e901ba4abfb809f363cf1351505002fc05e4..80b44c0540876871c4573723779d5c6e8fa42b0a 100644 (file)
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -880,15 +880,18 @@ static bool intel_hdmi_get_hw_state(struct intel_encoder *encoder,
        struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(&encoder->base);
        enum intel_display_power_domain power_domain;
        u32 tmp;
+       bool ret;
 
        power_domain = intel_display_port_power_domain(encoder);
-       if (!intel_display_power_is_enabled(dev_priv, power_domain))
+       if (!intel_display_power_get_if_enabled(dev_priv, power_domain))
                return false;
 
+       ret = false;
+
        tmp = I915_READ(intel_hdmi->hdmi_reg);
 
        if (!(tmp & SDVO_ENABLE))
-               return false;
+               goto out;
 
        if (HAS_PCH_CPT(dev))
                *pipe = PORT_TO_PIPE_CPT(tmp);
@@ -897,7 +900,12 @@ static bool intel_hdmi_get_hw_state(struct intel_encoder *encoder,
        else
                *pipe = PORT_TO_PIPE(tmp);
 
-       return true;
+       ret = true;
+
+out:
+       intel_display_power_put(dev_priv, power_domain);
+
+       return ret;
 }
 
 static void intel_hdmi_get_config(struct intel_encoder *encoder,