alistair23-linux/drivers/gpu/drm/msm/msm_atomic.c

/*
 * Copyright (C) 2014 Red Hat
 * Author: Rob Clark <robdclark@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "msm_drv.h"
#include "msm_gem.h"
#include "msm_kms.h"
#include "msm_gem.h"
#include "msm_fence.h"

static void msm_atomic_wait_for_commit_done(struct drm_device *dev,
		struct drm_atomic_state *old_state)
{
	struct drm_crtc *crtc;
	struct drm_crtc_state *new_crtc_state;
	struct msm_drm_private *priv = old_state->dev->dev_private;
	struct msm_kms *kms = priv->kms;
	int i;

	for_each_new_crtc_in_state(old_state, crtc, new_crtc_state, i) {
		if (!new_crtc_state->active)
			continue;

		kms->funcs->wait_for_crtc_commit_done(kms, crtc);
	}
}

int msm_atomic_prepare_fb(struct drm_plane *plane,
			  struct drm_plane_state *new_state)
{
	struct msm_drm_private *priv = plane->dev->dev_private;
	struct msm_kms *kms = priv->kms;
	struct drm_gem_object *obj;
	struct msm_gem_object *msm_obj;
	struct dma_fence *fence;

	if (!new_state->fb)
		return 0;

	obj = msm_framebuffer_bo(new_state->fb, 0);
	msm_obj = to_msm_bo(obj);
	fence = reservation_object_get_excl_rcu(msm_obj->resv);

	drm_atomic_set_fence_for_plane(new_state, fence);

	return msm_framebuffer_prepare(new_state->fb, kms->aspace);
}

static void msm_atomic_commit_tail(struct drm_atomic_state *state)
{
	struct drm_device *dev = state->dev;
	struct msm_drm_private *priv = dev->dev_private;
	struct msm_kms *kms = priv->kms;

	kms->funcs->prepare_commit(kms, state);

	drm_atomic_helper_commit_modeset_disables(dev, state);

	drm_atomic_helper_commit_planes(dev, state, 0);

	drm_atomic_helper_commit_modeset_enables(dev, state);

	/* NOTE: _wait_for_vblanks() only waits for vblank on
	 * enabled CRTCs.  So we end up faulting when disabling
	 * due to (potentially) unref'ing the outgoing fb's
	 * before the vblank when the disable has latched.
	 *
	 * But if it did wait on disabled (or newly disabled)
	 * CRTCs, that would be racy (ie. we could have missed
	 * the irq.  We need some way to poll for pipe shut
	 * down.  Or just live with occasionally hitting the
	 * timeout in the CRTC disable path (which really should
	 * not be critical path)
	 */

	msm_atomic_wait_for_commit_done(dev, state);

	kms->funcs->complete_commit(kms, state);

	drm_atomic_helper_wait_for_vblanks(dev, state);

	drm_atomic_helper_commit_hw_done(state);

	drm_atomic_helper_cleanup_planes(dev, state);
}

/* The (potentially) asynchronous part of the commit.  At this point
 * nothing can fail short of armageddon.
 */
static void commit_tail(struct drm_atomic_state *state)
{
	drm_atomic_helper_wait_for_fences(state->dev, state, false);

	drm_atomic_helper_wait_for_dependencies(state);

	msm_atomic_commit_tail(state);

	drm_atomic_helper_commit_cleanup_done(state);

	drm_atomic_state_put(state);
}

static void commit_work(struct work_struct *work)
{
	struct drm_atomic_state *state = container_of(work,
						      struct drm_atomic_state,
						      commit_work);
	commit_tail(state);
}

/**
 * drm_atomic_helper_commit - commit validated state object
 * @dev: DRM device
 * @state: the driver state object
 * @nonblock: nonblocking commit
 *
 * This function commits a with drm_atomic_helper_check() pre-validated state
 * object. This can still fail when e.g. the framebuffer reservation fails.
 *
 * RETURNS
 * Zero for success or -errno.
 */
int msm_atomic_commit(struct drm_device *dev,
		struct drm_atomic_state *state, bool nonblock)
{
	struct msm_drm_private *priv = dev->dev_private;
	struct drm_crtc *crtc;
	struct drm_crtc_state *crtc_state;
	struct drm_plane *plane;
	struct drm_plane_state *old_plane_state, *new_plane_state;
	int i, ret;

	/*
	 * Note that plane->atomic_async_check() should fail if we need
	 * to re-assign hwpipe or anything that touches global atomic
	 * state, so we'll never go down the async update path in those
	 * cases.
	 */
	if (state->async_update) {
		ret = drm_atomic_helper_prepare_planes(dev, state);
		if (ret)
			return ret;

		drm_atomic_helper_async_commit(dev, state);
		drm_atomic_helper_cleanup_planes(dev, state);
		return 0;
	}

	ret = drm_atomic_helper_setup_commit(state, nonblock);
	if (ret)
		return ret;

	INIT_WORK(&state->commit_work, commit_work);

	ret = drm_atomic_helper_prepare_planes(dev, state);
	if (ret)
		return ret;

	if (!nonblock) {
		ret = drm_atomic_helper_wait_for_fences(dev, state, true);
		if (ret)
			goto error;
	}

	/*
	 * This is the point of no return - everything below never fails except
	 * when the hw goes bonghits. Which means we can commit the new state on
	 * the software side now.
	 *
	 * swap driver private state while still holding state_lock
	 */
	BUG_ON(drm_atomic_helper_swap_state(state, true) < 0);

	/*
	 * This is the point of no return - everything below never fails except
	 * when the hw goes bonghits. Which means we can commit the new state on
	 * the software side now.
	 */

	/*
	 * Everything below can be run asynchronously without the need to grab
	 * any modeset locks at all under one conditions: It must be guaranteed
	 * that the asynchronous work has either been cancelled (if the driver
	 * supports it, which at least requires that the framebuffers get
	 * cleaned up with drm_atomic_helper_cleanup_planes()) or completed
	 * before the new state gets committed on the software side with
	 * drm_atomic_helper_swap_state().
	 *
	 * This scheme allows new atomic state updates to be prepared and
	 * checked in parallel to the asynchronous completion of the previous
	 * update. Which is important since compositors need to figure out the
	 * composition of the next frame right after having submitted the
	 * current layout.
	 */

	drm_atomic_state_get(state);
	if (nonblock)
		queue_work(system_unbound_wq, &state->commit_work);
	else
		commit_tail(state);

	return 0;

error:
	drm_atomic_helper_cleanup_planes(dev, state);
	return ret;
}