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Commit 935774cd authored by Brian Starkey's avatar Brian Starkey Committed by Liviu Dudau
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drm: Add writeback connector type 



Writeback connectors represent writeback engines which can write the
CRTC output to a memory framebuffer. Add a writeback connector type and
related support functions.

Drivers should initialize a writeback connector with
drm_writeback_connector_init() which takes care of setting up all the
writeback-specific details on top of the normal functionality of
drm_connector_init().

Writeback connectors have a WRITEBACK_FB_ID property, used to set the
output framebuffer, and a WRITEBACK_PIXEL_FORMATS blob used to expose the
supported writeback formats to userspace.

When a framebuffer is attached to a writeback connector with the
WRITEBACK_FB_ID property, it is used only once (for the commit in which
it was included), and userspace can never read back the value of
WRITEBACK_FB_ID. WRITEBACK_FB_ID can only be set if the connector is
attached to a CRTC.

Changes since v1:
 - Added drm_writeback.c + documentation
 - Added helper to initialize writeback connector in one go
 - Added core checks
 - Squashed into a single commit
 - Dropped the client cap
 - Writeback framebuffers are no longer persistent

Changes since v2:
 Daniel Vetter:
 - Subclass drm_connector to drm_writeback_connector
 - Relax check to allow CRTC to be set without an FB
 - Add some writeback_ prefixes
 - Drop PIXEL_FORMATS_SIZE property, as it was unnecessary
 Gustavo Padovan:
 - Add drm_writeback_job to handle writeback signalling centrally

Changes since v3:
 - Rebased
 - Rename PIXEL_FORMATS -> WRITEBACK_PIXEL_FORMATS

Chances since v4:
 - Embed a drm_encoder inside the drm_writeback_connector to
   reduce the amount of boilerplate code required from the drivers
   that are using it.

Changes since v5:
 - Added Rob Clark's atomic_commit() vfunc to connector helper
   funcs, so that writeback jobs are committed from atomic helpers
 - Updated create_writeback_properties() signature to return an
   error code rather than a boolean false for failure.
 - Free writeback job with the connector state rather than when
   doing the cleanup_work()

Changes since v7:
 - fix extraneous use of out_fence that is only introduced in a
   subsequent patch.

Changes since v8:
 - whitespace changes pull from subsequent patch

Changes since v9:
 - Revert the v6 changes that free the writeback job in the connector
   state cleanup and return to doing it in the cleanup_work() function

Signed-off-by: default avatarBrian Starkey <brian.starkey@arm.com>
[rebased and fixed conflicts]
Signed-off-by: default avatarMihail Atanassov <mihail.atanassov@arm.com>
[rebased and added atomic_commit() vfunc for writeback jobs]
Signed-off-by: default avatarRob Clark <robdclark@gmail.com>
Signed-off-by: default avatarLiviu Dudau <liviu.dudau@arm.com>
Reviewed-by: default avatarEric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/229037/
parent f664a526

Documentation/gpu/drm-kms.rst

+9 −0
Original line number Diff line number Diff line
@@ -373,6 +373,15 @@ Connector Functions Reference 
.. kernel-doc:: drivers/gpu/drm/drm_connector.c

   :export:



Writeback Connectors

--------------------



.. kernel-doc:: drivers/gpu/drm/drm_writeback.c

  :doc: overview



.. kernel-doc:: drivers/gpu/drm/drm_writeback.c

  :export:



Encoder Abstraction

===================

drivers/gpu/drm/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -18,7 +18,7 @@ drm-y := drm_auth.o drm_bufs.o drm_cache.o \ 
		drm_encoder.o drm_mode_object.o drm_property.o \

		drm_plane.o drm_color_mgmt.o drm_print.o \

		drm_dumb_buffers.o drm_mode_config.o drm_vblank.o \

		drm_syncobj.o drm_lease.o

		drm_syncobj.o drm_lease.o drm_writeback.o



drm-$(CONFIG_DRM_LIB_RANDOM) += lib/drm_random.o

drm-$(CONFIG_DRM_VM) += drm_vm.o

drivers/gpu/drm/drm_atomic.c

+124 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 
#include <drm/drm_atomic.h>

#include <drm/drm_mode.h>

#include <drm/drm_print.h>

#include <drm/drm_writeback.h>

#include <linux/sync_file.h>



#include "drm_crtc_internal.h"
@@ -690,6 +691,45 @@ static void drm_atomic_crtc_print_state(struct drm_printer *p, 
		crtc->funcs->atomic_print_state(p, state);

}



/**

 * drm_atomic_connector_check - check connector state

 * @connector: connector to check

 * @state: connector state to check

 *

 * Provides core sanity checks for connector state.

 *

 * RETURNS:

 * Zero on success, error code on failure

 */

static int drm_atomic_connector_check(struct drm_connector *connector,

		struct drm_connector_state *state)

{

	struct drm_crtc_state *crtc_state;

	struct drm_writeback_job *writeback_job = state->writeback_job;



	if ((connector->connector_type != DRM_MODE_CONNECTOR_WRITEBACK) || !writeback_job)

		return 0;



	if (writeback_job->fb && !state->crtc) {

		DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] framebuffer without CRTC\n",

				 connector->base.id, connector->name);

		return -EINVAL;

	}



	if (state->crtc)

		crtc_state = drm_atomic_get_existing_crtc_state(state->state,

								state->crtc);



	if (writeback_job->fb && !crtc_state->active) {

		DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] has framebuffer, but [CRTC:%d] is off\n",

				 connector->base.id, connector->name,

				 state->crtc->base.id);

		return -EINVAL;

	}



	return 0;

}



/**

 * drm_atomic_get_plane_state - get plane state

 * @state: global atomic state object
@@ -1321,6 +1361,12 @@ static int drm_atomic_connector_set_property(struct drm_connector *connector, 
			return -EINVAL;

		}

		state->content_protection = val;

	} else if (property == config->writeback_fb_id_property) {

		struct drm_framebuffer *fb = drm_framebuffer_lookup(dev, NULL, val);

		int ret = drm_atomic_set_writeback_fb_for_connector(state, fb);

		if (fb)

			drm_framebuffer_put(fb);

		return ret;

	} else if (connector->funcs->atomic_set_property) {

		return connector->funcs->atomic_set_property(connector,

				state, property, val);
@@ -1407,6 +1453,9 @@ drm_atomic_connector_get_property(struct drm_connector *connector, 
		*val = state->scaling_mode;

	} else if (property == connector->content_protection_property) {

		*val = state->content_protection;

	} else if (property == config->writeback_fb_id_property) {

		/* Writeback framebuffer is one-shot, write and forget */

		*val = 0;

	} else if (connector->funcs->atomic_get_property) {

		return connector->funcs->atomic_get_property(connector,

				state, property, val);
@@ -1631,6 +1680,70 @@ drm_atomic_set_crtc_for_connector(struct drm_connector_state *conn_state, 
}

EXPORT_SYMBOL(drm_atomic_set_crtc_for_connector);



/*

 * drm_atomic_get_writeback_job - return or allocate a writeback job

 * @conn_state: Connector state to get the job for

 *

 * Writeback jobs have a different lifetime to the atomic state they are

 * associated with. This convenience function takes care of allocating a job

 * if there isn't yet one associated with the connector state, otherwise

 * it just returns the existing job.

 *

 * Returns: The writeback job for the given connector state

 */

static struct drm_writeback_job *

drm_atomic_get_writeback_job(struct drm_connector_state *conn_state)

{

	WARN_ON(conn_state->connector->connector_type != DRM_MODE_CONNECTOR_WRITEBACK);



	if (!conn_state->writeback_job)

		conn_state->writeback_job =

			kzalloc(sizeof(*conn_state->writeback_job), GFP_KERNEL);



	return conn_state->writeback_job;

}



/**

 * drm_atomic_set_writeback_fb_for_connector - set writeback framebuffer

 * @conn_state: atomic state object for the connector

 * @fb: fb to use for the connector

 *

 * This is used to set the framebuffer for a writeback connector, which outputs

 * to a buffer instead of an actual physical connector.

 * Changing the assigned framebuffer requires us to grab a reference to the new

 * fb and drop the reference to the old fb, if there is one. This function

 * takes care of all these details besides updating the pointer in the

 * state object itself.

 *

 * Note: The only way conn_state can already have an fb set is if the commit

 * sets the property more than once.

 *

 * See also: drm_writeback_connector_init()

 *

 * Returns: 0 on success

 */

int drm_atomic_set_writeback_fb_for_connector(

		struct drm_connector_state *conn_state,

		struct drm_framebuffer *fb)

{

	struct drm_writeback_job *job =

		drm_atomic_get_writeback_job(conn_state);

	if (!job)

		return -ENOMEM;



	drm_framebuffer_assign(&job->fb, fb);



	if (fb)

		DRM_DEBUG_ATOMIC("Set [FB:%d] for connector state %p\n",

				 fb->base.id, conn_state);

	else

		DRM_DEBUG_ATOMIC("Set [NOFB] for connector state %p\n",

				 conn_state);



	return 0;

}

EXPORT_SYMBOL(drm_atomic_set_writeback_fb_for_connector);



/**

 * drm_atomic_add_affected_connectors - add connectors for crtc

 * @state: atomic state
@@ -1752,6 +1865,8 @@ int drm_atomic_check_only(struct drm_atomic_state *state) 
	struct drm_plane_state *plane_state;

	struct drm_crtc *crtc;

	struct drm_crtc_state *crtc_state;

	struct drm_connector *conn;

	struct drm_connector_state *conn_state;

	int i, ret = 0;



	DRM_DEBUG_ATOMIC("checking %p\n", state);
@@ -1774,6 +1889,15 @@ int drm_atomic_check_only(struct drm_atomic_state *state) 
		}

	}



	for_each_new_connector_in_state(state, conn, conn_state, i) {

		ret = drm_atomic_connector_check(conn, conn_state);

		if (ret) {

			DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] atomic core check failed\n",

					 conn->base.id, conn->name);

			return ret;

		}

	}



	if (config->funcs->atomic_check)

		ret = config->funcs->atomic_check(state->dev, state);

drivers/gpu/drm/drm_atomic_helper.c

+25 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 
#include <drm/drm_plane_helper.h>

#include <drm/drm_crtc_helper.h>

#include <drm/drm_atomic_helper.h>

#include <drm/drm_writeback.h>

#include <linux/dma-fence.h>



#include "drm_crtc_helper_internal.h"
@@ -1172,6 +1173,25 @@ void drm_atomic_helper_commit_modeset_disables(struct drm_device *dev, 
}

EXPORT_SYMBOL(drm_atomic_helper_commit_modeset_disables);



static void drm_atomic_helper_commit_writebacks(struct drm_device *dev,

						struct drm_atomic_state *old_state)

{

	struct drm_connector *connector;

	struct drm_connector_state *new_conn_state;

	int i;



	for_each_new_connector_in_state(old_state, connector, new_conn_state, i) {

		const struct drm_connector_helper_funcs *funcs;



		funcs = connector->helper_private;



		if (new_conn_state->writeback_job && new_conn_state->writeback_job->fb) {

			WARN_ON(connector->connector_type != DRM_MODE_CONNECTOR_WRITEBACK);

			funcs->atomic_commit(connector, new_conn_state->writeback_job);

		}

	}

}



/**

 * drm_atomic_helper_commit_modeset_enables - modeset commit to enable outputs

 * @dev: DRM device
@@ -1251,6 +1271,8 @@ void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev, 


		drm_bridge_enable(encoder->bridge);

	}



	drm_atomic_helper_commit_writebacks(dev, old_state);

}

EXPORT_SYMBOL(drm_atomic_helper_commit_modeset_enables);
@@ -3647,6 +3669,9 @@ __drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector, 
	if (state->crtc)

		drm_connector_get(connector);

	state->commit = NULL;



	/* Don't copy over a writeback job, they are used only once */

	state->writeback_job = NULL;

}

EXPORT_SYMBOL(__drm_atomic_helper_connector_duplicate_state);

drivers/gpu/drm/drm_connector.c

+3 −1
Original line number Diff line number Diff line
@@ -87,6 +87,7 @@ static struct drm_conn_prop_enum_list drm_connector_enum_list[] = { 
	{ DRM_MODE_CONNECTOR_VIRTUAL, "Virtual" },

	{ DRM_MODE_CONNECTOR_DSI, "DSI" },

	{ DRM_MODE_CONNECTOR_DPI, "DPI" },

	{ DRM_MODE_CONNECTOR_WRITEBACK, "Writeback" },

};



void drm_connector_ida_init(void)
@@ -253,7 +254,8 @@ int drm_connector_init(struct drm_device *dev, 
	config->num_connector++;

	spin_unlock_irq(&config->connector_list_lock);



	if (connector_type != DRM_MODE_CONNECTOR_VIRTUAL)

	if (connector_type != DRM_MODE_CONNECTOR_VIRTUAL &&

	    connector_type != DRM_MODE_CONNECTOR_WRITEBACK)

		drm_object_attach_property(&connector->base,

					      config->edid_property,

					      0);