drm/tegra: plane: Implement zpos plane property for older Tegras

Older Tegra's do not support plane's Z position handling in hardware,
but the hardware provides knobs to implement it in software.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

3 files changed, 244 insertions, 96 deletions

diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
index a4dd866fc8be..51581d9da509 100644
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -163,28 +163,89 @@ static void tegra_plane_setup_blending_legacy(struct tegra_plane *plane)
                          BLEND_COLOR_KEY_NONE;
         u32 blendnokey = BLEND_WEIGHT1(255) | BLEND_WEIGHT0(255);
         struct tegra_plane_state *state;
+        u32 blending[2];
         unsigned int i;
 
+        /* disable blending for non-overlapping case */
+        tegra_plane_writel(plane, blendnokey, DC_WIN_BLEND_NOKEY);
+        tegra_plane_writel(plane, foreground, DC_WIN_BLEND_1WIN);
+
         state = to_tegra_plane_state(plane->base.state);
 
-        /* alpha contribution is 1 minus sum of overlapping windows */
-        for (i = 0; i < 3; i++) {
-                if (state->dependent[i])
-                        background[i] |= BLEND_CONTROL_DEPENDENT;
-        }
+        if (state->opaque) {
+                /*
+                 * Since custom fix-weight blending isn't utilized and weight
+                 * of top window is set to max, we can enforce dependent
+                 * blending which in this case results in transparent bottom
+                 * window if top window is opaque and if top window enables
+                 * alpha blending, then bottom window is getting alpha value
+                 * of 1 minus the sum of alpha components of the overlapping
+                 * plane.
+                 */
+                background[0] |= BLEND_CONTROL_DEPENDENT;
+                background[1] |= BLEND_CONTROL_DEPENDENT;
 
-        /* enable alpha blending if pixel format has an alpha component */
-        if (!state->opaque)
+                /*
+                 * The region where three windows overlap is the intersection
+                 * of the two regions where two windows overlap. It contributes
+                 * to the area if all of the windows on top of it have an alpha
+                 * component.
+                 */
+                switch (state->base.normalized_zpos) {
+                case 0:
+                        if (state->blending[0].alpha &&
+                            state->blending[1].alpha)
+                                background[2] |= BLEND_CONTROL_DEPENDENT;
+                        break;
+
+                case 1:
+                        background[2] |= BLEND_CONTROL_DEPENDENT;
+                        break;
+                }
+        } else {
+                /*
+                 * Enable alpha blending if pixel format has an alpha
+                 * component.
+                 */
                 foreground |= BLEND_CONTROL_ALPHA;
 
-        /*
-         * Disable blending and assume Window A is the bottom-most window,
-         * Window C is the top-most window and Window B is in the middle.
-         */
-        tegra_plane_writel(plane, blendnokey, DC_WIN_BLEND_NOKEY);
-        tegra_plane_writel(plane, foreground, DC_WIN_BLEND_1WIN);
+                /*
+                 * If any of the windows on top of this window is opaque, it
+                 * will completely conceal this window within that area. If
+                 * top window has an alpha component, it is blended over the
+                 * bottom window.
+                 */
+                for (i = 0; i < 2; i++) {
+                        if (state->blending[i].alpha &&
+                            state->blending[i].top)
+                                background[i] |= BLEND_CONTROL_DEPENDENT;
+                }
 
-        switch (plane->index) {
+                switch (state->base.normalized_zpos) {
+                case 0:
+                        if (state->blending[0].alpha &&
+                            state->blending[1].alpha)
+                                background[2] |= BLEND_CONTROL_DEPENDENT;
+                        break;
+
+                case 1:
+                        /*
+                         * When both middle and topmost windows have an alpha,
+                         * these windows a mixed together and then the result
+                         * is blended over the bottom window.
+                         */
+                        if (state->blending[0].alpha &&
+                            state->blending[0].top)
+                                background[2] |= BLEND_CONTROL_ALPHA;
+
+                        if (state->blending[1].alpha &&
+                            state->blending[1].top)
+                                background[2] |= BLEND_CONTROL_ALPHA;
+                        break;
+                }
+        }
+
+        switch (state->base.normalized_zpos) {
         case 0:
                 tegra_plane_writel(plane, background[0], DC_WIN_BLEND_2WIN_X);
                 tegra_plane_writel(plane, background[1], DC_WIN_BLEND_2WIN_Y);
@@ -192,8 +253,21 @@ static void tegra_plane_setup_blending_legacy(struct tegra_plane *plane)
                 break;
 
         case 1:
-                tegra_plane_writel(plane, foreground, DC_WIN_BLEND_2WIN_X);
-                tegra_plane_writel(plane, background[1], DC_WIN_BLEND_2WIN_Y);
+                /*
+                 * If window B / C is topmost, then X / Y registers are
+                 * matching the order of blending[...] state indices,
+                 * otherwise a swap is required.
+                 */
+                if (!state->blending[0].top && state->blending[1].top) {
+                        blending[0] = foreground;
+                        blending[1] = background[1];
+                } else {
+                        blending[0] = background[0];
+                        blending[1] = foreground;
+                }
+
+                tegra_plane_writel(plane, blending[0], DC_WIN_BLEND_2WIN_X);
+                tegra_plane_writel(plane, blending[1], DC_WIN_BLEND_2WIN_Y);
                 tegra_plane_writel(plane, background[2], DC_WIN_BLEND_3WIN_XY);
                 break;
 
@@ -525,14 +599,14 @@ static int tegra_plane_atomic_check(struct drm_plane *plane,
         struct tegra_bo_tiling *tiling = &plane_state->tiling;
         struct tegra_plane *tegra = to_tegra_plane(plane);
         struct tegra_dc *dc = to_tegra_dc(state->crtc);
-        unsigned int format;
         int err;
 
         /* no need for further checks if the plane is being disabled */
         if (!state->crtc)
                 return 0;
 
-        err = tegra_plane_format(state->fb->format->format, &format,
+        err = tegra_plane_format(state->fb->format->format,
+                                 &plane_state->format,
                                  &plane_state->swap);
         if (err < 0)
                 return err;
@@ -544,21 +618,11 @@ static int tegra_plane_atomic_check(struct drm_plane *plane,
          * be emulated by disabling alpha blending for the plane.
          */
         if (!dc->soc->supports_blending) {
-                if (!tegra_plane_format_has_alpha(format)) {
-                        err = tegra_plane_format_get_alpha(format, &format);
-                        if (err < 0)
-                                return err;
-
-                        plane_state->opaque = true;
-                } else {
-                        plane_state->opaque = false;
-                }
-
-                tegra_plane_check_dependent(tegra, plane_state);
+                err = tegra_plane_setup_legacy_state(tegra, plane_state);
+                if (err < 0)
+                        return err;
         }
 
-        plane_state->format = format;
-
         err = tegra_fb_get_tiling(state->fb, tiling);
         if (err < 0)
                 return err;
@@ -710,9 +774,7 @@ static struct drm_plane *tegra_primary_plane_create(struct drm_device *drm,
         }
 
         drm_plane_helper_add(&plane->base, &tegra_plane_helper_funcs);
-
-        if (dc->soc->supports_blending)
-                drm_plane_create_zpos_property(&plane->base, 0, 0, 255);
+        drm_plane_create_zpos_property(&plane->base, plane->index, 0, 255);
 
         return &plane->base;
 }
@@ -989,9 +1051,7 @@ static struct drm_plane *tegra_dc_overlay_plane_create(struct drm_device *drm,
         }
 
         drm_plane_helper_add(&plane->base, &tegra_plane_helper_funcs);
-
-        if (dc->soc->supports_blending)
-                drm_plane_create_zpos_property(&plane->base, 0, 0, 255);
+        drm_plane_create_zpos_property(&plane->base, plane->index, 0, 255);
 
         return &plane->base;
 }
diff --git a/drivers/gpu/drm/tegra/plane.c b/drivers/gpu/drm/tegra/plane.c
index 176ef46c615c..0406c2ef432c 100644
--- a/drivers/gpu/drm/tegra/plane.c
+++ b/drivers/gpu/drm/tegra/plane.c
@@ -23,6 +23,7 @@ static void tegra_plane_destroy(struct drm_plane *plane)
 
 static void tegra_plane_reset(struct drm_plane *plane)
 {
+        struct tegra_plane *p = to_tegra_plane(plane);
         struct tegra_plane_state *state;
 
         if (plane->state)
@@ -35,6 +36,8 @@ static void tegra_plane_reset(struct drm_plane *plane)
         if (state) {
                 plane->state = &state->base;
                 plane->state->plane = plane;
+                plane->state->zpos = p->index;
+                plane->state->normalized_zpos = p->index;
         }
 }
 
@@ -55,8 +58,8 @@ tegra_plane_atomic_duplicate_state(struct drm_plane *plane)
         copy->swap = state->swap;
         copy->opaque = state->opaque;
 
-        for (i = 0; i < 3; i++)
-                copy->dependent[i] = state->dependent[i];
+        for (i = 0; i < 2; i++)
+                copy->blending[i] = state->blending[i];
 
         return &copy->base;
 }
@@ -267,24 +270,8 @@ static bool __drm_format_has_alpha(u32 format)
         return false;
 }
 
-/*
- * This is applicable to Tegra20 and Tegra30 only where the opaque formats can
- * be emulated using the alpha formats and alpha blending disabled.
- */
-bool tegra_plane_format_has_alpha(unsigned int format)
-{
-        switch (format) {
-        case WIN_COLOR_DEPTH_B5G5R5A1:
-        case WIN_COLOR_DEPTH_A1B5G5R5:
-        case WIN_COLOR_DEPTH_R8G8B8A8:
-        case WIN_COLOR_DEPTH_B8G8R8A8:
-                return true;
-        }
-
-        return false;
-}
-
-int tegra_plane_format_get_alpha(unsigned int opaque, unsigned int *alpha)
+static int tegra_plane_format_get_alpha(unsigned int opaque,
+                                        unsigned int *alpha)
 {
         if (tegra_plane_format_is_yuv(opaque, NULL)) {
                 *alpha = opaque;
@@ -316,6 +303,67 @@ int tegra_plane_format_get_alpha(unsigned int opaque, unsigned int *alpha)
         return -EINVAL;
 }
 
+/*
+ * This is applicable to Tegra20 and Tegra30 only where the opaque formats can
+ * be emulated using the alpha formats and alpha blending disabled.
+ */
+static int tegra_plane_setup_opacity(struct tegra_plane *tegra,
+                                     struct tegra_plane_state *state)
+{
+        unsigned int format;
+        int err;
+
+        switch (state->format) {
+        case WIN_COLOR_DEPTH_B5G5R5A1:
+        case WIN_COLOR_DEPTH_A1B5G5R5:
+        case WIN_COLOR_DEPTH_R8G8B8A8:
+        case WIN_COLOR_DEPTH_B8G8R8A8:
+                state->opaque = false;
+                break;
+
+        default:
+                err = tegra_plane_format_get_alpha(state->format, &format);
+                if (err < 0)
+                        return err;
+
+                state->format = format;
+                state->opaque = true;
+                break;
+        }
+
+        return 0;
+}
+
+static int tegra_plane_check_transparency(struct tegra_plane *tegra,
+                                          struct tegra_plane_state *state)
+{
+        struct drm_plane_state *old, *plane_state;
+        struct drm_plane *plane;
+
+        old = drm_atomic_get_old_plane_state(state->base.state, &tegra->base);
+
+        /* check if zpos / transparency changed */
+        if (old->normalized_zpos == state->base.normalized_zpos &&
+            to_tegra_plane_state(old)->opaque == state->opaque)
+                return 0;
+
+        /* include all sibling planes into this commit */
+        drm_for_each_plane(plane, tegra->base.dev) {
+                struct tegra_plane *p = to_tegra_plane(plane);
+
+                /* skip this plane and planes on different CRTCs */
+                if (p == tegra || p->dc != tegra->dc)
+                        continue;
+
+                plane_state = drm_atomic_get_plane_state(state->base.state,
+                                                         plane);
+                if (IS_ERR(plane_state))
+                        return PTR_ERR(plane_state);
+        }
+
+        return 1;
+}
+
 static unsigned int tegra_plane_get_overlap_index(struct tegra_plane *plane,
                                                   struct tegra_plane *other)
 {
@@ -336,61 +384,98 @@ static unsigned int tegra_plane_get_overlap_index(struct tegra_plane *plane,
         return index;
 }
 
-void tegra_plane_check_dependent(struct tegra_plane *tegra,
-                                 struct tegra_plane_state *state)
+static void tegra_plane_update_transparency(struct tegra_plane *tegra,
+                                            struct tegra_plane_state *state)
 {
-        struct drm_plane_state *old, *new;
+        struct drm_plane_state *new;
         struct drm_plane *plane;
-        unsigned int zpos[2];
         unsigned int i;
 
-        for (i = 0; i < 2; i++)
-                zpos[i] = 0;
-
-        for_each_oldnew_plane_in_state(state->base.state, plane, old, new, i) {
+        for_each_new_plane_in_state(state->base.state, plane, new, i) {
                 struct tegra_plane *p = to_tegra_plane(plane);
                 unsigned index;
 
                 /* skip this plane and planes on different CRTCs */
-                if (p == tegra || new->crtc != state->base.crtc)
+                if (p == tegra || p->dc != tegra->dc)
                         continue;
 
                 index = tegra_plane_get_overlap_index(tegra, p);
 
-                state->dependent[index] = false;
+                if (new->fb && __drm_format_has_alpha(new->fb->format->format))
+                        state->blending[index].alpha = true;
+                else
+                        state->blending[index].alpha = false;
+
+                if (new->normalized_zpos > state->base.normalized_zpos)
+                        state->blending[index].top = true;
+                else
+                        state->blending[index].top = false;
 
                 /*
-                 * If any of the other planes is on top of this plane and uses
-                 * a format with an alpha component, mark this plane as being
-                 * dependent, meaning it's alpha value will be 1 minus the sum
-                 * of alpha components of the overlapping planes.
+                 * Missing framebuffer means that plane is disabled, in this
+                 * case mark B / C window as top to be able to differentiate
+                 * windows indices order in regards to zPos for the middle
+                 * window X / Y registers programming.
                  */
-                if (p->index > tegra->index) {
-                        if (__drm_format_has_alpha(new->fb->format->format))
-                                state->dependent[index] = true;
-
-                        /* keep track of the Z position */
-                        zpos[index] = p->index;
-                }
+                if (!new->fb)
+                        state->blending[index].top = (index == 1);
         }
+}
+
+static int tegra_plane_setup_transparency(struct tegra_plane *tegra,
+                                          struct tegra_plane_state *state)
+{
+        struct tegra_plane_state *tegra_state;
+        struct drm_plane_state *new;
+        struct drm_plane *plane;
+        int err;
 
         /*
-         * The region where three windows overlap is the intersection of the
-         * two regions where two windows overlap. It contributes to the area
-         * if any of the windows on top of it have an alpha component.
+         * If planes zpos / transparency changed, sibling planes blending
+         * state may require adjustment and in this case they will be included
+         * into this atom commit, otherwise blending state is unchanged.
          */
-        for (i = 0; i < 2; i++)
-                state->dependent[2] = state->dependent[2] ||
-                                      state->dependent[i];
+        err = tegra_plane_check_transparency(tegra, state);
+        if (err <= 0)
+                return err;
 
         /*
-         * However, if any of the windows on top of this window is opaque, it
-         * will completely conceal this window within that area, so avoid the
-         * window from contributing to the area.
+         * All planes are now in the atomic state, walk them up and update
+         * transparency state for each plane.
          */
-        for (i = 0; i < 2; i++) {
-                if (zpos[i] > tegra->index)
-                        state->dependent[2] = state->dependent[2] &&
-                                              state->dependent[i];
+        drm_for_each_plane(plane, tegra->base.dev) {
+                struct tegra_plane *p = to_tegra_plane(plane);
+
+                /* skip planes on different CRTCs */
+                if (p->dc != tegra->dc)
+                        continue;
+
+                new = drm_atomic_get_new_plane_state(state->base.state, plane);
+                tegra_state = to_tegra_plane_state(new);
+
+                /*
+                 * There is no need to update blending state for the disabled
+                 * plane.
+                 */
+                if (new->fb)
+                        tegra_plane_update_transparency(p, tegra_state);
         }
+
+        return 0;
+}
+
+int tegra_plane_setup_legacy_state(struct tegra_plane *tegra,
+                                   struct tegra_plane_state *state)
+{
+        int err;
+
+        err = tegra_plane_setup_opacity(tegra, state);
+        if (err < 0)
+                return err;
+
+        err = tegra_plane_setup_transparency(tegra, state);
+        if (err < 0)
+                return err;
+
+        return 0;
 }
diff --git a/drivers/gpu/drm/tegra/plane.h b/drivers/gpu/drm/tegra/plane.h
index 6938719e7e5d..7360ddfafee8 100644
--- a/drivers/gpu/drm/tegra/plane.h
+++ b/drivers/gpu/drm/tegra/plane.h
@@ -34,6 +34,11 @@ static inline struct tegra_plane *to_tegra_plane(struct drm_plane *plane)
         return container_of(plane, struct tegra_plane, base);
 }
 
+struct tegra_plane_legacy_blending_state {
+        bool alpha;
+        bool top;
+};
+
 struct tegra_plane_state {
         struct drm_plane_state base;
 
@@ -42,8 +47,8 @@ struct tegra_plane_state {
         u32 swap;
 
         /* used for legacy blending support only */
+        struct tegra_plane_legacy_blending_state blending[2];
         bool opaque;
-        bool dependent[3];
 };
 
 static inline struct tegra_plane_state *
@@ -62,9 +67,7 @@ int tegra_plane_state_add(struct tegra_plane *plane,
 
 int tegra_plane_format(u32 fourcc, u32 *format, u32 *swap);
 bool tegra_plane_format_is_yuv(unsigned int format, bool *planar);
-bool tegra_plane_format_has_alpha(unsigned int format);
-int tegra_plane_format_get_alpha(unsigned int opaque, unsigned int *alpha);
-void tegra_plane_check_dependent(struct tegra_plane *tegra,
-                                 struct tegra_plane_state *state);
+int tegra_plane_setup_legacy_state(struct tegra_plane *tegra,
+                                   struct tegra_plane_state *state);
 
 #endif /* TEGRA_PLANE_H */