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

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commit 3a62234680 upstream.

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>
Cc: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric Anholt
2016-11-04 15:58:38 -07:00
committed by Greg Kroah-Hartman
parent dd0b0e22a5
commit 2bbcbc2447
3 changed files with 12 additions and 5 deletions
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9
drivers/gpu/drm/vc4/vc4_drv.c
View File

@@ -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:
args->value = true;

6
drivers/gpu/drm/vc4/vc4_gem.c
View File

@@ -711,8 +711,10 @@ 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);

2
drivers/gpu/drm/vc4/vc4_v3d.c
View File

@@ -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;