drm/i915/ibx: Ensure the HW is powered during PLL HW 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: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1455296121-4742-4-git-send-email-imre.deak@intel.com

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index a38b0ab406f168cbc8aad16dee6faf2f26e4f06b..82b05ca94cf80a2690e9f2c994fa36acc0427bf5 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -13658,7 +13658,7 @@ static bool ibx_pch_dpll_get_hw_state(struct drm_i915_private *dev_priv,
 {
        uint32_t val;
 
-       if (!intel_display_power_is_enabled(dev_priv, POWER_DOMAIN_PLLS))
+       if (!intel_display_power_get_if_enabled(dev_priv, POWER_DOMAIN_PLLS))
                return false;
 
        val = I915_READ(PCH_DPLL(pll->id));
@@ -13666,6 +13666,8 @@ static bool ibx_pch_dpll_get_hw_state(struct drm_i915_private *dev_priv,
        hw_state->fp0 = I915_READ(PCH_FP0(pll->id));
        hw_state->fp1 = I915_READ(PCH_FP1(pll->id));
 
+       intel_display_power_put(dev_priv, POWER_DOMAIN_PLLS);
+
        return val & DPLL_VCO_ENABLE;
 }