drm/i915: Ensure the HW is powered during HW access in assert_pipe

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/1455296121-4742-6-git-send-email-imre.deak@intel.com
(cherry picked from commit 4feed0ebfa45879bc422c9a0bfa3cffec82ea60a)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 7934c45366ff26e92fec0c4d9811bbe591e8cbcc..46947fffd5998074555c95ce8d373343aac20bd6 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1351,18 +1351,21 @@ void assert_pipe(struct drm_i915_private *dev_priv,
        bool cur_state;
        enum transcoder cpu_transcoder = intel_pipe_to_cpu_transcoder(dev_priv,
                                                                      pipe);
+       enum intel_display_power_domain power_domain;
 
        /* if we need the pipe quirk it must be always on */
        if ((pipe == PIPE_A && dev_priv->quirks & QUIRK_PIPEA_FORCE) ||
            (pipe == PIPE_B && dev_priv->quirks & QUIRK_PIPEB_FORCE))
                state = true;
 
-       if (!intel_display_power_is_enabled(dev_priv,
-                               POWER_DOMAIN_TRANSCODER(cpu_transcoder))) {
-               cur_state = false;
-       } else {
+       power_domain = POWER_DOMAIN_TRANSCODER(cpu_transcoder);
+       if (intel_display_power_get_if_enabled(dev_priv, power_domain)) {
                u32 val = I915_READ(PIPECONF(cpu_transcoder));
                cur_state = !!(val & PIPECONF_ENABLE);
+
+               intel_display_power_put(dev_priv, power_domain);
+       } else {
+               cur_state = false;
        }
 
        I915_STATE_WARN(cur_state != state,