[RFC PATCH v2 8/9] drm: writeback: Add out-fences for writeback connectors
Gustavo Padovan
gustavo at padovan.org
Wed Oct 26 21:40:29 UTC 2016
2016-10-26 Brian Starkey <brian.starkey at arm.com>:
> Add the OUT_FENCE_PTR property to writeback connectors, to enable
> userspace to get a fence which will signal once the writeback is
> complete.
>
> A timeline is added to drm_connector for use by the writeback
> out-fences. It is up to drivers to check for a fence in the
> connector_state and signal the it appropriately when their writeback has
> finished.
>
> It is not allowed to request an out-fence without a framebuffer attached
> to the connector.
>
> Signed-off-by: Brian Starkey <brian.starkey at arm.com>
> ---
> drivers/gpu/drm/drm_atomic.c | 60 +++++++++++++++++++++++---
> drivers/gpu/drm/drm_atomic_helper.c | 5 ++-
> drivers/gpu/drm/drm_writeback.c | 80 +++++++++++++++++++++++++++++++++++
> include/drm/drm_connector.h | 14 ++++++
> include/drm/drm_writeback.h | 2 +
> 5 files changed, 155 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index 3f8fc97..061ea13 100644
> --- a/drivers/gpu/drm/drm_atomic.c
> +++ b/drivers/gpu/drm/drm_atomic.c
> @@ -30,6 +30,7 @@
> #include <drm/drm_atomic.h>
> #include <drm/drm_mode.h>
> #include <drm/drm_plane_helper.h>
> +#include <drm/drm_writeback.h>
> #include <linux/sync_file.h>
>
> #include "drm_crtc_internal.h"
> @@ -646,6 +647,12 @@ static int drm_atomic_connector_check(struct drm_connector *connector,
> return -EINVAL;
> }
>
> + if (state->out_fence && !state->fb) {
> + DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] requesting out-fence without framebuffer\n",
> + connector->base.id, connector->name);
> + return -EINVAL;
> + }
> +
> return 0;
> }
>
> @@ -1047,6 +1054,8 @@ int drm_atomic_connector_set_property(struct drm_connector *connector,
> drm_atomic_set_fb_for_connector(state, fb);
> if (fb)
> drm_framebuffer_unreference(fb);
> + } else if (property == config->prop_out_fence_ptr) {
> + state->out_fence_ptr = u64_to_user_ptr(val);
We need to move this out of the conn_state. For my v6 on CRTC out fences
I added drm_atomic_set_out_fence_for_crtc() and
drm_atomic_get_out_fence_for_crtc(). See padovan/fences.
> } else if (connector->funcs->atomic_set_property) {
> return connector->funcs->atomic_set_property(connector,
> state, property, val);
> @@ -1088,6 +1097,8 @@ drm_atomic_connector_get_property(struct drm_connector *connector,
> } else if (property == config->writeback_fb_id_property) {
> /* Writeback framebuffer is one-shot, write and forget */
> *val = 0;
> + } else if (property == config->prop_out_fence_ptr) {
> + *val = 0;
> } else if (connector->funcs->atomic_get_property) {
> return connector->funcs->atomic_get_property(connector,
> state, property, val);
> @@ -1736,6 +1747,39 @@ static int setup_out_fence(struct drm_out_fence_state *fence_state,
> return 0;
> }
>
> +static int setup_connector_out_fences(struct drm_atomic_state *state,
> + struct drm_out_fence_state *fence_state,
> + int *fence_idx)
> +{
> + struct drm_connector *conn;
> + struct drm_connector_state *conn_state;
> + int i, ret;
> +
> + for_each_connector_in_state(state, conn, conn_state, i) {
> + struct fence *fence;
> +
> + if (!conn_state->out_fence_ptr)
> + continue;
> +
> + fence = drm_writeback_get_out_fence(conn, conn_state);
> + if (!fence)
> + return -ENOMEM;
> +
> + ret = setup_out_fence(&fence_state[(*fence_idx)++],
> + conn_state->out_fence_ptr,
> + fence);
> + if (ret) {
> + fence_put(fence);
> + return ret;
> + }
> +
> + /* One-time usage only */
> + conn_state->out_fence_ptr = NULL;
> + }
> +
> + return 0;
> +}
> +
> int drm_mode_atomic_ioctl(struct drm_device *dev,
> void *data, struct drm_file *file_priv)
> {
> @@ -1868,8 +1912,8 @@ retry:
> drm_mode_object_unreference(obj);
> }
>
> - fence_state = kcalloc(dev->mode_config.num_crtc, sizeof(*fence_state),
> - GFP_KERNEL);
> + fence_state = kcalloc(dev->mode_config.num_crtc + state->num_connector,
> + sizeof(*fence_state), GFP_KERNEL);
> if (!fence_state) {
> ret = -ENOMEM;
> goto out;
> @@ -1929,10 +1973,16 @@ retry:
> * Below we call drm_atomic_state_free for it.
> */
> ret = drm_atomic_check_only(state);
> - } else if (arg->flags & DRM_MODE_ATOMIC_NONBLOCK) {
> - ret = drm_atomic_nonblocking_commit(state);
> } else {
> - ret = drm_atomic_commit(state);
> + ret = setup_connector_out_fences(state, fence_state,
> + &fence_idx);
> + if (ret)
> + goto out;
I'd do this before this block. At the DRM_MODE_ATOMIC_TEST_ONLY or we
check or we commit. Moreover you should check if out_fences
are not set with TEST_ONLY.
> +
> + if (arg->flags & DRM_MODE_ATOMIC_NONBLOCK)
> + ret = drm_atomic_nonblocking_commit(state);
> + else
> + ret = drm_atomic_commit(state);
> }
>
> if (!ret)
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index bba8672..88da299 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -3234,8 +3234,9 @@ __drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector,
> if (state->crtc)
> drm_connector_reference(connector);
>
> - /* Don't copy over framebuffers, they are used only once */
> + /* Don't copy over framebuffers or fences, they are used only once */
> state->fb = NULL;
> + state->out_fence = NULL;
> }
> EXPORT_SYMBOL(__drm_atomic_helper_connector_duplicate_state);
>
> @@ -3365,6 +3366,8 @@ __drm_atomic_helper_connector_destroy_state(struct drm_connector_state *state)
> drm_connector_unreference(state->connector);
> if (state->fb)
> drm_framebuffer_unreference(state->fb);
> +
> + fence_put(state->out_fence);
> }
> EXPORT_SYMBOL(__drm_atomic_helper_connector_destroy_state);
>
> diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c
> index 5a6e0ad..4a6ef30 100644
> --- a/drivers/gpu/drm/drm_writeback.c
> +++ b/drivers/gpu/drm/drm_writeback.c
> @@ -11,6 +11,7 @@
> #include <drm/drm_crtc.h>
> #include <drm/drm_property.h>
> #include <drm/drmP.h>
> +#include <linux/fence.h>
>
> /**
> * DOC: overview
> @@ -32,6 +33,16 @@
> * explicitly cleared in order to make a subsequent commit which doesn't use
> * writeback.
> *
> + * Unlike with planes, when a writeback framebuffer is removed by userspace DRM
> + * makes no attempt to remove it from active use by the connector. This is
> + * because no method is provided to abort a writeback operation, and in any
> + * case making a new commit whilst a writeback is ongoing is undefined (see
> + * OUT_FENCE_PTR below). As soon as the current writeback is finished, the
> + * framebuffer will automatically no longer be in active use. As it will also
> + * have already been removed from the framebuffer list, there will be no way for
> + * any userspace application to retrieve a reference to it in the intervening
> + * period.
> + *
> * Writeback connectors have several additional properties, which userspace
> * can use to query and control them:
> *
> @@ -52,8 +63,48 @@
> * "PIXEL_FORMATS_SIZE":
> * Immutable unsigned range property storing the number of entries in the
> * PIXEL_FORMATS array.
> + *
> + * "OUT_FENCE_PTR":
> + * Userspace can provide the address of a 64-bit integer in this property,
> + * which will be filled with a sync_file file descriptor by the kernel.
> + * The sync_file will signal when the associated writeback has finished.
> + * Userspace should wait for this fence to signal before making another
> + * commit affecting any of the same CRTCs, Planes or Connectors.
> + * **Failure to do so will result in undefined behaviour.**
> + * For this reason it is strongly recommended that all userspace
> + * applications making use of writeback connectors *always* retrieve an
> + * out-fence for the commit and use it appropriately.
> + * From userspace, this property will always read as zero.
> */
>
> +#define fence_to_connector(x) container_of(x->lock, struct drm_connector, fence_lock)
> +
> +static const char *drm_writeback_fence_get_driver_name(struct fence *fence)
> +{
> + struct drm_connector *connector = fence_to_connector(fence);
> +
> + return connector->dev->driver->name;
> +}
> +
> +static const char *drm_writeback_fence_get_timeline_name(struct fence *fence)
> +{
> + struct drm_connector *connector = fence_to_connector(fence);
> +
> + return connector->timeline_name;
> +}
> +
> +static bool drm_writeback_fence_enable_signaling(struct fence *fence)
> +{
> + return true;
> +}
> +
> +static const struct fence_ops drm_writeback_fence_ops = {
> + .get_driver_name = drm_writeback_fence_get_driver_name,
> + .get_timeline_name = drm_writeback_fence_get_timeline_name,
> + .enable_signaling = drm_writeback_fence_enable_signaling,
> + .wait = fence_default_wait,
> +};
> +
> /**
> * create_writeback_properties - Create writeback connector-specific properties
> * @dev: DRM device
> @@ -136,6 +187,14 @@ int drm_writeback_connector_init(struct drm_device *dev,
> if (ret)
> goto fail;
>
> + connector->fence_context = fence_context_alloc(1);
> + spin_lock_init(&connector->fence_lock);
> + snprintf(connector->timeline_name, sizeof(connector->timeline_name),
> + "CONNECTOR:%d", connector->base.id);
> +
> + drm_object_attach_property(&connector->base,
> + config->prop_out_fence_ptr, 0);
> +
> drm_object_attach_property(&connector->base,
> config->writeback_fb_id_property, 0);
>
> @@ -155,3 +214,24 @@ fail:
> return ret;
> }
> EXPORT_SYMBOL(drm_writeback_connector_init);
> +
> +struct fence *drm_writeback_get_out_fence(struct drm_connector *connector,
> + struct drm_connector_state *conn_state)
> +{
> + struct fence *fence;
> +
> + if (WARN_ON(connector->connector_type != DRM_MODE_CONNECTOR_WRITEBACK))
> + return NULL;
> +
> + fence = kzalloc(sizeof(*fence), GFP_KERNEL);
> + if (!fence)
> + return NULL;
> +
> + fence_init(fence, &drm_writeback_fence_ops, &connector->fence_lock,
> + connector->fence_context, ++connector->fence_seqno);
> +
> + conn_state->out_fence = fence_get(fence);
> +
> + return fence;
> +}
> +EXPORT_SYMBOL(drm_writeback_get_out_fence);
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index a5e3778..7d40537 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -199,6 +199,7 @@ int drm_display_info_set_bus_formats(struct drm_display_info *info,
> * @best_encoder: can be used by helpers and drivers to select the encoder
> * @state: backpointer to global drm_atomic_state
> * @fb: Writeback framebuffer, for DRM_MODE_CONNECTOR_WRITEBACK
> + * @out_fence: Fence which will clear when the framebuffer write has finished
> */
> struct drm_connector_state {
> struct drm_connector *connector;
> @@ -216,6 +217,9 @@ struct drm_connector_state {
> struct drm_atomic_state *state;
>
> struct drm_framebuffer *fb; /* do not write directly, use drm_atomic_set_fb_for_connector() */
> +
> + struct fence *out_fence;
> + u64 __user *out_fence_ptr;
> };
>
> /**
> @@ -546,6 +550,10 @@ struct drm_cmdline_mode {
> * @tile_v_loc: vertical location of this tile
> * @tile_h_size: horizontal size of this tile.
> * @tile_v_size: vertical size of this tile.
> + * @fence_context: context for fence signalling
> + * @fence_lock: fence lock for the fence context
> + * @fence_seqno: seqno variable to create fences
> + * @timeline_name: fence timeline name
> *
> * Each connector may be connected to one or more CRTCs, or may be clonable by
> * another connector if they can share a CRTC. Each connector also has a specific
> @@ -694,6 +702,12 @@ struct drm_connector {
> uint8_t num_h_tile, num_v_tile;
> uint8_t tile_h_loc, tile_v_loc;
> uint16_t tile_h_size, tile_v_size;
> +
> + /* fence timelines info for DRM out-fences */
> + unsigned int fence_context;
> + spinlock_t fence_lock;
> + unsigned long fence_seqno;
> + char timeline_name[32];
> };
>
> #define obj_to_connector(x) container_of(x, struct drm_connector, base)
> diff --git a/include/drm/drm_writeback.h b/include/drm/drm_writeback.h
> index afdc2742..01f33bc 100644
> --- a/include/drm/drm_writeback.h
> +++ b/include/drm/drm_writeback.h
> @@ -16,4 +16,6 @@ int drm_writeback_connector_init(struct drm_device *dev,
> const struct drm_connector_funcs *funcs,
> u32 *formats, int n_formats);
>
> +struct fence *drm_writeback_get_out_fence(struct drm_connector *connector,
> + struct drm_connector_state *conn_state);
> #endif
> --
> 1.7.9.5
>
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