drm/panfrost: Add madvise and shrinker support

Add support for madvise and a shrinker similar to other drivers. This
allows userspace to mark BOs which can be freed when there is memory
pressure.

Unlike other implementations, we don't depend on struct_mutex. The
driver maintains a list of BOs which can be freed when the shrinker
is called. Access to the list is serialized with the shrinker_lock.

Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Acked-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190805143358.21245-2-robh@kernel.org

1 files changed, 38 insertions, 0 deletions

diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
index b187daa4da85..926d021ee202 100644
--- a/drivers/gpu/drm/panfrost/panfrost_drv.c
+++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
@@ -333,6 +333,38 @@ static int panfrost_ioctl_get_bo_offset(struct drm_device *dev, void *data,
 	return 0;
 }
 
+static int panfrost_ioctl_madvise(struct drm_device *dev, void *data,
+				  struct drm_file *file_priv)
+{
+	struct drm_panfrost_madvise *args = data;
+	struct panfrost_device *pfdev = dev->dev_private;
+	struct drm_gem_object *gem_obj;
+
+	gem_obj = drm_gem_object_lookup(file_priv, args->handle);
+	if (!gem_obj) {
+		DRM_DEBUG("Failed to look up GEM BO %d\n", args->handle);
+		return -ENOENT;
+	}
+
+	args->retained = drm_gem_shmem_madvise(gem_obj, args->madv);
+
+	if (args->retained) {
+		struct panfrost_gem_object *bo = to_panfrost_bo(gem_obj);
+
+		mutex_lock(&pfdev->shrinker_lock);
+
+		if (args->madv == PANFROST_MADV_DONTNEED)
+			list_add_tail(&bo->base.madv_list, &pfdev->shrinker_list);
+		else if (args->madv == PANFROST_MADV_WILLNEED)
+			list_del_init(&bo->base.madv_list);
+
+		mutex_unlock(&pfdev->shrinker_lock);
+	}
+
+	drm_gem_object_put_unlocked(gem_obj);
+	return 0;
+}
+
 int panfrost_unstable_ioctl_check(void)
 {
 	if (!unstable_ioctls)
@@ -384,6 +416,7 @@ static const struct drm_ioctl_desc panfrost_drm_driver_ioctls[] = {
 	PANFROST_IOCTL(GET_BO_OFFSET,	get_bo_offset,	DRM_RENDER_ALLOW),
 	PANFROST_IOCTL(PERFCNT_ENABLE,	perfcnt_enable,	DRM_RENDER_ALLOW),
 	PANFROST_IOCTL(PERFCNT_DUMP,	perfcnt_dump,	DRM_RENDER_ALLOW),
+	PANFROST_IOCTL(MADVISE,		madvise,	DRM_RENDER_ALLOW),
 };
 
 DEFINE_DRM_GEM_SHMEM_FOPS(panfrost_drm_driver_fops);
@@ -432,6 +465,8 @@ static int panfrost_probe(struct platform_device *pdev)
 	pfdev->ddev = ddev;
 
 	spin_lock_init(&pfdev->mm_lock);
+	mutex_init(&pfdev->shrinker_lock);
+	INIT_LIST_HEAD(&pfdev->shrinker_list);
 
 	/* 4G enough for now. can be 48-bit */
 	drm_mm_init(&pfdev->mm, SZ_32M >> PAGE_SHIFT, (SZ_4G - SZ_32M) >> PAGE_SHIFT);
@@ -462,6 +497,8 @@ static int panfrost_probe(struct platform_device *pdev)
 	if (err < 0)
 		goto err_out1;
 
+	panfrost_gem_shrinker_init(ddev);
+
 	return 0;
 
 err_out1:
@@ -478,6 +515,7 @@ static int panfrost_remove(struct platform_device *pdev)
 	struct drm_device *ddev = pfdev->ddev;
 
 	drm_dev_unregister(ddev);
+	panfrost_gem_shrinker_cleanup(ddev);
 	pm_runtime_get_sync(pfdev->dev);
 	pm_runtime_put_sync_autosuspend(pfdev->dev);
 	pm_runtime_disable(pfdev->dev);