[PATCH] drm: Don't force all planes to be added to the state due to zpos

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

We don't want all planes to be added to the state whenever a
plane with fixed zpos gets enabled/disabled. This is true
especially for eg. cursor planes on i915, as we want cursor
updates to go through w/o throttling. Same holds for drivers
that don't support zpos at all (i915 actually falls into this
category right now since we've not yet added zpos support).

Allow drivers more freedom by letting them deal with zpos
themselves instead of doing it in drm_atomic_helper_check_planes()
unconditionally. Easiest solution seems to be to move the call
up to drm_atomic_helper_check(). But as some drivers might want
to use that function without the zpos handling, let's provide
two variants: the normal one, and one that deals with zpos.

Cc: Marek Szyprowski <m.szyprowski at samsung.com>
Cc: Benjamin Gaignard <benjamin.gaignard at linaro.org>
Cc: Vincent Abriou <vincent.abriou at st.com>
Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Cc: Inki Dae <inki.dae at samsung.com>
Cc: Joonyoung Shim <jy0922.shim at samsung.com>
Cc: Seung-Woo Kim <sw0312.kim at samsung.com>
Cc: Kyungmin Park <kyungmin.park at samsung.com>
Cc: Lyude <cpaul at redhat.com>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: stable at vger.kernel.org
Fixes: 44d1240d006c ("drm: add generic zpos property")
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/drm_atomic_helper.c    | 46 +++++++++++++++++++++++++++++++---
 drivers/gpu/drm/exynos/exynos_drm_fb.c |  2 +-
 drivers/gpu/drm/rcar-du/rcar_du_kms.c  |  2 +-
 drivers/gpu/drm/sti/sti_drv.c          |  2 +-
 include/drm/drm_atomic_helper.h        |  2 ++
 5 files changed, 47 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index c3f83476f996..cd19281cdefb 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -594,10 +594,6 @@ drm_atomic_helper_check_planes(struct drm_device *dev,
 	struct drm_plane_state *plane_state;
 	int i, ret = 0;
 
-	ret = drm_atomic_normalize_zpos(dev, state);
-	if (ret)
-		return ret;
-
 	for_each_plane_in_state(state, plane, plane_state, i) {
 		const struct drm_plane_helper_funcs *funcs;
 
@@ -673,6 +669,48 @@ int drm_atomic_helper_check(struct drm_device *dev,
 }
 EXPORT_SYMBOL(drm_atomic_helper_check);
 
+/**
+ * drm_atomic_helper_check_with_zpos - validate state object, dealing with zpos
+ * @dev: DRM device
+ * @state: the driver state object
+ *
+ * Check the state object to see if the requested state is physically possible.
+ * Only crtcs and planes have check callbacks, so for any additional (global)
+ * checking that a driver needs it can simply wrap that around this function.
+ * Drivers without such needs can directly use this as their ->atomic_check()
+ * callback.
+ *
+ * This just wraps the two parts of the state checking for planes and modeset
+ * state in the default order: First it calls drm_atomic_helper_check_modeset(),
+ * followed by drm_atomic_normalize_zpos(), and finally
+ * drm_atomic_helper_check_planes(). The assumption is that the
+ * ->atomic_check functions depend upon an updated adjusted_mode.clock to
+ * e.g. properly compute watermarks.
+ *
+ * RETURNS:
+ * Zero for success or -errno
+ */
+int drm_atomic_helper_check_with_zpos(struct drm_device *dev,
+				      struct drm_atomic_state *state)
+{
+	int ret;
+
+	ret = drm_atomic_helper_check_modeset(dev, state);
+	if (ret)
+		return ret;
+
+	ret = drm_atomic_normalize_zpos(dev, state);
+	if (ret)
+		return ret;
+
+	ret = drm_atomic_helper_check_planes(dev, state);
+	if (ret)
+		return ret;
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_atomic_helper_check_with_zpos);
+
 static void
 disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
 {
diff --git a/drivers/gpu/drm/exynos/exynos_drm_fb.c b/drivers/gpu/drm/exynos/exynos_drm_fb.c
index 40ce841eb952..5c0930af01fa 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_fb.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_fb.c
@@ -190,7 +190,7 @@ dma_addr_t exynos_drm_fb_dma_addr(struct drm_framebuffer *fb, int index)
 static const struct drm_mode_config_funcs exynos_drm_mode_config_funcs = {
 	.fb_create = exynos_user_fb_create,
 	.output_poll_changed = exynos_drm_output_poll_changed,
-	.atomic_check = drm_atomic_helper_check,
+	.atomic_check = drm_atomic_helper_check_with_zpos,
 	.atomic_commit = exynos_atomic_commit,
 };
 
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
index bd9c3bb9252c..2cfd35f3f2f6 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
@@ -231,7 +231,7 @@ static int rcar_du_atomic_check(struct drm_device *dev,
 	struct rcar_du_device *rcdu = dev->dev_private;
 	int ret;
 
-	ret = drm_atomic_helper_check(dev, state);
+	ret = drm_atomic_helper_check_with_zpos(dev, state);
 	if (ret < 0)
 		return ret;
 
diff --git a/drivers/gpu/drm/sti/sti_drv.c b/drivers/gpu/drm/sti/sti_drv.c
index 2784919a7366..df5f150021d0 100644
--- a/drivers/gpu/drm/sti/sti_drv.c
+++ b/drivers/gpu/drm/sti/sti_drv.c
@@ -248,7 +248,7 @@ static void sti_output_poll_changed(struct drm_device *ddev)
 static const struct drm_mode_config_funcs sti_mode_config_funcs = {
 	.fb_create = drm_fb_cma_create,
 	.output_poll_changed = sti_output_poll_changed,
-	.atomic_check = drm_atomic_helper_check,
+	.atomic_check = drm_atomic_helper_check_with_zpos,
 	.atomic_commit = sti_atomic_commit,
 };
 
diff --git a/include/drm/drm_atomic_helper.h b/include/drm/drm_atomic_helper.h
index 7ff92b09fd9c..b1e7193c9d1c 100644
--- a/include/drm/drm_atomic_helper.h
+++ b/include/drm/drm_atomic_helper.h
@@ -40,6 +40,8 @@ int drm_atomic_helper_check_planes(struct drm_device *dev,
 			       struct drm_atomic_state *state);
 int drm_atomic_helper_check(struct drm_device *dev,
 			    struct drm_atomic_state *state);
+int drm_atomic_helper_check_with_zpos(struct drm_device *dev,
+				      struct drm_atomic_state *state);
 void drm_atomic_helper_commit_tail(struct drm_atomic_state *state);
 int drm_atomic_helper_commit(struct drm_device *dev,
 			     struct drm_atomic_state *state,
-- 
2.7.4