drm/msm/mdp5: add skeletal mdp5_state

Add basic state duplication/apply mechanism.  Following commits will
move actual global hw state into this.

The state_lock allows multiple concurrent updates to proceed as long as
they don't both try to alter global state.  The ww_mutex mechanism will
trigger backoff in case of deadlock between multiple threads trying to
update state.
Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Archit Taneja <architt@codeaurora.org>

drivers/gpu/drm/msm/mdp/mdp5/mdp5_kms.c

@@ -72,6 +72,39 @@ static int mdp5_hw_init(struct msm_kms *kms)
 	return 0;
 }
 
+struct mdp5_state *mdp5_get_state(struct drm_atomic_state *s)
+{
+	struct msm_drm_private *priv = s->dev->dev_private;
+	struct mdp5_kms *mdp5_kms = to_mdp5_kms(to_mdp_kms(priv->kms));
+	struct msm_kms_state *state = to_kms_state(s);
+	struct mdp5_state *new_state;
+	int ret;
+
+	if (state->state)
+		return state->state;
+
+	ret = drm_modeset_lock(&mdp5_kms->state_lock, s->acquire_ctx);
+	if (ret)
+		return ERR_PTR(ret);
+
+	new_state = kmalloc(sizeof(*mdp5_kms->state), GFP_KERNEL);
+	if (!new_state)
+		return ERR_PTR(-ENOMEM);
+
+	/* Copy state: */
+	/* TODO */
+
+	state->state = new_state;
+
+	return new_state;
+}
+
+static void mdp5_swap_state(struct msm_kms *kms, struct drm_atomic_state *state)
+{
+	struct mdp5_kms *mdp5_kms = to_mdp5_kms(to_mdp_kms(kms));
+	swap(to_kms_state(state)->state, mdp5_kms->state);
+}
+
 static void mdp5_prepare_commit(struct msm_kms *kms, struct drm_atomic_state *state)
 {
 	struct mdp5_kms *mdp5_kms = to_mdp5_kms(to_mdp_kms(kms));
@@ -140,6 +173,7 @@ static const struct mdp_kms_funcs kms_funcs = {
 		.irq             = mdp5_irq,
 		.enable_vblank   = mdp5_enable_vblank,
 		.disable_vblank  = mdp5_disable_vblank,
+		.swap_state      = mdp5_swap_state,
 		.prepare_commit  = mdp5_prepare_commit,
 		.complete_commit = mdp5_complete_commit,
 		.wait_for_crtc_commit_done = mdp5_wait_for_crtc_commit_done,
@@ -645,6 +679,8 @@ static void mdp5_destroy(struct platform_device *pdev)
 
 	if (mdp5_kms->rpm_enabled)
 		pm_runtime_disable(&pdev->dev);
+
+	kfree(mdp5_kms->state);
 }
 
 static int construct_pipes(struct mdp5_kms *mdp5_kms, int cnt,
@@ -729,6 +765,13 @@ static int mdp5_init(struct platform_device *pdev, struct drm_device *dev)
 	mdp5_kms->dev = dev;
 	mdp5_kms->pdev = pdev;
 
+	drm_modeset_lock_init(&mdp5_kms->state_lock);
+	mdp5_kms->state = kzalloc(sizeof(*mdp5_kms->state), GFP_KERNEL);
+	if (!mdp5_kms->state) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+
 	mdp5_kms->mmio = msm_ioremap(pdev, "mdp_phys", "MDP5");
 	if (IS_ERR(mdp5_kms->mmio)) {
 		ret = PTR_ERR(mdp5_kms->mmio);

drivers/gpu/drm/msm/mdp/mdp5/mdp5_kms.h

@@ -27,6 +27,8 @@
 #include "mdp5_pipe.h"
 #include "mdp5_smp.h"
 
+struct mdp5_state;
+
 struct mdp5_kms {
 	struct mdp_kms base;
 
@@ -40,6 +42,11 @@ struct mdp5_kms {
 	struct mdp5_cfg_handler *cfg;
 	uint32_t caps;	/* MDP capabilities (MDP_CAP_XXX bits) */
 
+	/**
+	 * Global atomic state.  Do not access directly, use mdp5_get_state()
+	 */
+	struct mdp5_state *state;
+	struct drm_modeset_lock state_lock;
 
 	/* mapper-id used to request GEM buffer mapped for scanout: */
 	int id;
@@ -69,6 +76,21 @@ struct mdp5_kms {
 };
 #define to_mdp5_kms(x) container_of(x, struct mdp5_kms, base)
 
+/* Global atomic state for tracking resources that are shared across
+ * multiple kms objects (planes/crtcs/etc).
+ *
+ * For atomic updates which require modifying global state,
+ */
+struct mdp5_state {
+	uint32_t dummy;
+};
+
+struct mdp5_state *__must_check
+mdp5_get_state(struct drm_atomic_state *s);
+
+/* Atomic plane state.  Subclasses the base drm_plane_state in order to
+ * track assigned hwpipe and hw specific state.
+ */
 struct mdp5_plane_state {
 	struct drm_plane_state base;