drm/i915/gen9: Check for DC state mismatch

The DMC can incorrectly run off and allow DC states on it's own. We
don't know the root-cause for this yet but this patch makes it more
visible.

Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1455808874-22089-2-git-send-email-mika.kuoppala@intel.com
(cherry picked from commit 832dba889e27487c3087149f1039acc3feb89003)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index e7cd311..b0847b9 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -751,6 +751,7 @@ struct intel_csr {
        uint32_t mmio_count;
        i915_reg_t mmioaddr[8];
        uint32_t mmiodata[8];
+       uint32_t dc_state;
 };
 
 #define DEV_INFO_FOR_EACH_FLAG(func, sep) \

diff --git a/drivers/gpu/drm/i915/intel_csr.c b/drivers/gpu/drm/i915/intel_csr.c
index 9bb63a8..647d85e 100644 (file)
--- a/drivers/gpu/drm/i915/intel_csr.c
+++ b/drivers/gpu/drm/i915/intel_csr.c
@@ -240,6 +240,8 @@ void intel_csr_load_program(struct drm_i915_private *dev_priv)
                I915_WRITE(dev_priv->csr.mmioaddr[i],
                           dev_priv->csr.mmiodata[i]);
        }
+
+       dev_priv->csr.dc_state = 0;
 }
 
 static uint32_t *parse_csr_fw(struct drm_i915_private *dev_priv,

diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index 89dcc99..19e6ff6 100644 (file)
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -494,10 +494,18 @@ static void gen9_set_dc_state(struct drm_i915_private *dev_priv, uint32_t state)
        val = I915_READ(DC_STATE_EN);
        DRM_DEBUG_KMS("Setting DC state from %02x to %02x\n",
                      val & mask, state);
+
+       /* Check if DMC is ignoring our DC state requests */
+       if ((val & mask) != dev_priv->csr.dc_state)
+               DRM_ERROR("DC state mismatch (0x%x -> 0x%x)\n",
+                         dev_priv->csr.dc_state, val & mask);
+
        val &= ~mask;
        val |= state;
        I915_WRITE(DC_STATE_EN, val);
        POSTING_READ(DC_STATE_EN);
+
+       dev_priv->csr.dc_state = val & mask;
 }
 
 void bxt_enable_dc9(struct drm_i915_private *dev_priv)