drm/i915: add render standby support
Render standy allows the GPU to power down the render unit when idle.
In order for this to work, it needs a page of graphics memory to save
state. This patch allocates that page and enables the feature on
supported chipsets.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 099f420..8945656 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4296,6 +4296,42 @@
} else if (IS_I830(dev)) {
I915_WRITE(DSPCLK_GATE_D, OVRUNIT_CLOCK_GATE_DISABLE);
}
+
+ /*
+ * GPU can automatically power down the render unit if given a page
+ * to save state.
+ */
+ if (I915_HAS_RC6(dev)) {
+ struct drm_gem_object *pwrctx;
+ struct drm_i915_gem_object *obj_priv;
+ int ret;
+
+ pwrctx = drm_gem_object_alloc(dev, 4096);
+ if (!pwrctx) {
+ DRM_DEBUG("failed to alloc power context, RC6 disabled\n");
+ goto out;
+ }
+
+ ret = i915_gem_object_pin(pwrctx, 4096);
+ if (ret) {
+ DRM_ERROR("failed to pin power context: %d\n", ret);
+ drm_gem_object_unreference(pwrctx);
+ goto out;
+ }
+
+ i915_gem_object_set_to_gtt_domain(pwrctx, 1);
+
+ obj_priv = pwrctx->driver_private;
+
+ I915_WRITE(PWRCTXA, obj_priv->gtt_offset | PWRCTX_EN);
+ I915_WRITE(MCHBAR_RENDER_STANDBY,
+ I915_READ(MCHBAR_RENDER_STANDBY) & ~RCX_SW_EXIT);
+
+ dev_priv->pwrctx = pwrctx;
+ }
+
+out:
+ return;
}
/* Set up chip specific display functions */
@@ -4450,6 +4486,11 @@
if (dev_priv->display.disable_fbc)
dev_priv->display.disable_fbc(dev);
+ if (dev_priv->pwrctx) {
+ i915_gem_object_unpin(dev_priv->pwrctx);
+ drm_gem_object_unreference(dev_priv->pwrctx);
+ }
+
drm_mode_config_cleanup(dev);
}