drm/vc4: Use runtime autosuspend to avoid thrashing V3D power state.

The pm_runtime_put() we were using immediately released power on the
device, which meant that we were generally turning the device off and
on once per frame.  In many profiles I've looked at, that added up to
about 1% of CPU time, but this could get worse in the case of frequent
rendering and readback (as may happen in X rendering).  By keeping the
device on until we've been idle for a couple of frames, we drop the
overhead of runtime PM down to sub-.1%.

Signed-off-by: Eric Anholt <eric@anholt.net>

diff --git a/drivers/gpu/drm/vc4/vc4_drv.c b/drivers/gpu/drm/vc4/vc4_drv.c
index b087404c2784bace5d3796acad57319b4fd9d5b3..7abfe088f2d109706103a37ba342b6a16227dfb3 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_drv.c
+++ b/drivers/gpu/drm/vc4/vc4_drv.c
@@ -61,21 +61,24 @@ static int vc4_get_param_ioctl(struct drm_device *dev, void *data,
                if (ret < 0)
                        return ret;
                args->value = V3D_READ(V3D_IDENT0);
-               pm_runtime_put(&vc4->v3d->pdev->dev);
+               pm_runtime_mark_last_busy(&vc4->v3d->pdev->dev);
+               pm_runtime_put_autosuspend(&vc4->v3d->pdev->dev);
                break;
        case DRM_VC4_PARAM_V3D_IDENT1:
                ret = pm_runtime_get_sync(&vc4->v3d->pdev->dev);
                if (ret < 0)
                        return ret;
                args->value = V3D_READ(V3D_IDENT1);
-               pm_runtime_put(&vc4->v3d->pdev->dev);
+               pm_runtime_mark_last_busy(&vc4->v3d->pdev->dev);
+               pm_runtime_put_autosuspend(&vc4->v3d->pdev->dev);
                break;
        case DRM_VC4_PARAM_V3D_IDENT2:
                ret = pm_runtime_get_sync(&vc4->v3d->pdev->dev);
                if (ret < 0)
                        return ret;
                args->value = V3D_READ(V3D_IDENT2);
-               pm_runtime_put(&vc4->v3d->pdev->dev);
+               pm_runtime_mark_last_busy(&vc4->v3d->pdev->dev);
+               pm_runtime_put_autosuspend(&vc4->v3d->pdev->dev);
                break;
        case DRM_VC4_PARAM_SUPPORTS_BRANCHES:
        case DRM_VC4_PARAM_SUPPORTS_ETC1:

diff --git a/drivers/gpu/drm/vc4/vc4_gem.c b/drivers/gpu/drm/vc4/vc4_gem.c
index 303f23c962206836d8c95786ad835d7625e10ee8..db920771bfb5641c9d5d8e53a8f73cf7ee501bb7 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_gem.c
+++ b/drivers/gpu/drm/vc4/vc4_gem.c
@@ -709,8 +709,10 @@ vc4_complete_exec(struct drm_device *dev, struct vc4_exec_info *exec)
        }
 
        mutex_lock(&vc4->power_lock);
-       if (--vc4->power_refcount == 0)
-               pm_runtime_put(&vc4->v3d->pdev->dev);
+       if (--vc4->power_refcount == 0) {
+               pm_runtime_mark_last_busy(&vc4->v3d->pdev->dev);
+               pm_runtime_put_autosuspend(&vc4->v3d->pdev->dev);
+       }
        mutex_unlock(&vc4->power_lock);
 
        kfree(exec);

diff --git a/drivers/gpu/drm/vc4/vc4_v3d.c b/drivers/gpu/drm/vc4/vc4_v3d.c
index e6d3c6028341e447df293cab525713ac10d8ee5e..7cc346ad9b0baed63701d1fae8f0306aa7713129 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_v3d.c
+++ b/drivers/gpu/drm/vc4/vc4_v3d.c
@@ -222,6 +222,8 @@ static int vc4_v3d_bind(struct device *dev, struct device *master, void *data)
                return ret;
        }
 
+       pm_runtime_use_autosuspend(dev);
+       pm_runtime_set_autosuspend_delay(dev, 40); /* a little over 2 frames. */
        pm_runtime_enable(dev);
 
        return 0;