drm/i915: Reorder media/render reset on g4x

Ville found a reference to WaMediaResetBeforeFullReset which we presume
means that we should simply do the media reset first.

References: https://bugs.freedesktop.org/show_bug.cgi?id=100942
Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170518204811.7408-2-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index b27cc00..7922264 100644 (file)
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -1468,16 +1468,9 @@ static int g4x_do_reset(struct drm_i915_private *dev_priv, unsigned engine_mask)
        struct pci_dev *pdev = dev_priv->drm.pdev;
        int ret;
 
-       pci_write_config_byte(pdev, I915_GDRST,
-                             GRDOM_RENDER | GRDOM_RESET_ENABLE);
-       ret =  wait_for(g4x_reset_complete(pdev), 500);
-       if (ret) {
-               DRM_DEBUG_DRIVER("Wait for render reset failed\n");
-               goto out;
-       }
-
        /* WaVcpClkGateDisableForMediaReset:ctg,elk */
-       I915_WRITE(VDECCLK_GATE_D, I915_READ(VDECCLK_GATE_D) | VCP_UNIT_CLOCK_GATE_DISABLE);
+       I915_WRITE(VDECCLK_GATE_D,
+                  I915_READ(VDECCLK_GATE_D) | VCP_UNIT_CLOCK_GATE_DISABLE);
        POSTING_READ(VDECCLK_GATE_D);
 
        pci_write_config_byte(pdev, I915_GDRST,
@@ -1485,14 +1478,24 @@ static int g4x_do_reset(struct drm_i915_private *dev_priv, unsigned engine_mask)
        ret =  wait_for(g4x_reset_complete(pdev), 500);
        if (ret) {
                DRM_DEBUG_DRIVER("Wait for media reset failed\n");
+               goto out;
        }
 
-       /* WaVcpClkGateDisableForMediaReset:ctg,elk */
-       I915_WRITE(VDECCLK_GATE_D, I915_READ(VDECCLK_GATE_D) & ~VCP_UNIT_CLOCK_GATE_DISABLE);
-       POSTING_READ(VDECCLK_GATE_D);
+       pci_write_config_byte(pdev, I915_GDRST,
+                             GRDOM_RENDER | GRDOM_RESET_ENABLE);
+       ret =  wait_for(g4x_reset_complete(pdev), 500);
+       if (ret) {
+               DRM_DEBUG_DRIVER("Wait for render reset failed\n");
+               goto out;
+       }
 
 out:
        pci_write_config_byte(pdev, I915_GDRST, 0);
+
+       I915_WRITE(VDECCLK_GATE_D,
+                  I915_READ(VDECCLK_GATE_D) & ~VCP_UNIT_CLOCK_GATE_DISABLE);
+       POSTING_READ(VDECCLK_GATE_D);
+
        return ret;
 }