[PATCH RFC v6 01/10] drm: Introduce pixel_source DRM plane property

Jessica Zhang
2023-08-29T00:07:22Z

Add support for pixel_source property to drm_plane and related
documentation. In addition, force pixel_source to
DRM_PLANE_PIXEL_SOURCE_FB in DRM_IOCTL_MODE_SETPLANE as to not break
legacy userspace.

This enum property will allow user to specify a pixel source for the
plane. Possible pixel sources will be defined in the
drm_plane_pixel_source enum.

Currently, the only pixel sources are DRM_PLANE_PIXEL_SOURCE_FB (the
default value) and DRM_PLANE_PIXEL_SOURCE_NONE.

Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
---
drivers/gpu/drm/drm_atomic_state_helper.c | 1 +
drivers/gpu/drm/drm_atomic_uapi.c | 4 ++
drivers/gpu/drm/drm_blend.c | 90 +++++++++++++++++++++++++++++++
drivers/gpu/drm/drm_plane.c | 19 +++++--
include/drm/drm_blend.h | 2 +
include/drm/drm_plane.h | 21 ++++++++
6 files changed, 133 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_state_helper.c b/drivers/gpu/drm/drm_atomic_state_helper.c
index 784e63d70a42..01638c51ce0a 100644
--- a/drivers/gpu/drm/drm_atomic_state_helper.c
+++ b/drivers/gpu/drm/drm_atomic_state_helper.c
@@ -252,6 +252,7 @@ void __drm_atomic_helper_plane_state_reset(struct drm_plane_state *plane_state,

plane_state->alpha = DRM_BLEND_ALPHA_OPAQUE;
plane_state->pixel_blend_mode = DRM_MODE_BLEND_PREMULTI;
+ plane_state->pixel_source = DRM_PLANE_PIXEL_SOURCE_FB;

if (plane->color_encoding_property) {
if (!drm_object_property_get_default_value(&plane->base,
diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index d867e7f9f2cd..454f980e16c9 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -544,6 +544,8 @@ static int drm_atomic_plane_set_property(struct drm_plane *plane,
state->src_w = val;
} else if (property == config->prop_src_h) {
state->src_h = val;
+ } else if (property == plane->pixel_source_property) {
+ state->pixel_source = val;
} else if (property == plane->alpha_property) {
state->alpha = val;
} else if (property == plane->blend_mode_property) {
@@ -616,6 +618,8 @@ drm_atomic_plane_get_property(struct drm_plane *plane,
*val = state->src_w;
} else if (property == config->prop_src_h) {
*val = state->src_h;
+ } else if (property == plane->pixel_source_property) {
+ *val = state->pixel_source;
} else if (property == plane->alpha_property) {
*val = state->alpha;
} else if (property == plane->blend_mode_property) {
diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c
index 6e74de833466..c3c57bae06b7 100644
--- a/drivers/gpu/drm/drm_blend.c
+++ b/drivers/gpu/drm/drm_blend.c
@@ -185,6 +185,21 @@
* plane does not expose the "alpha" property, then this is
* assumed to be 1.0
*
+ * pixel_source:
+ * pixel_source is set up with drm_plane_create_pixel_source_property().
+ * It is used to toggle the active source of pixel data for the plane.
+ * The plane will only display data from the set pixel_source -- any
+ * data from other sources will be ignored.
+ *
+ * Possible values:
+ *
+ * "NONE":
+ * No active pixel source.
+ * Committing with a NONE pixel source will disable the plane.
+ *
+ * "FB":
+ * Framebuffer source set by the "FB_ID" property.
+ *
* Note that all the property extensions described here apply either to the
* plane or the CRTC (e.g. for the background color, which currently is not
* exposed and assumed to be black).
@@ -615,3 +630,78 @@ int drm_plane_create_blend_mode_property(struct drm_plane *plane,
return 0;
}
EXPORT_SYMBOL(drm_plane_create_blend_mode_property);
+
+static const struct drm_prop_enum_list drm_pixel_source_enum_list[] = {
+ { DRM_PLANE_PIXEL_SOURCE_NONE, "NONE" },
+ { DRM_PLANE_PIXEL_SOURCE_FB, "FB" },
+};
+
+/**
+ * drm_plane_create_pixel_source_property - create a new pixel source property
+ * @plane: DRM plane
+ * @extra_sources: Bitmask of additional supported pixel_sources for the driver.
+ * DRM_PLANE_PIXEL_SOURCE_FB and DRM_PLANE_PIXEL_SOURCE_NONE will
+ * always be enabled as supported sources.
+ *
+ * This creates a new property describing the current source of pixel data for the
+ * plane. The pixel_source will be initialized as DRM_PLANE_PIXEL_SOURCE_FB by default.
+ *
+ * Drivers can set a custom default source by overriding the pixel_source value in
+ * drm_plane_funcs.reset()
+ *
+ * The property is exposed to userspace as an enumeration property called
+ * "pixel_source" and has the following enumeration values:
+ *
+ * "NONE":
+ * No active pixel source
+ *
+ * "FB":
+ * Framebuffer pixel source
+ *
+ * Returns:
+ * Zero on success, negative errno on failure.
+ */
+int drm_plane_create_pixel_source_property(struct drm_plane *plane,
+ unsigned long extra_sources)
+{
+ struct drm_device *dev = plane->dev;
+ struct drm_property *prop;
+ static const unsigned int valid_source_mask = BIT(DRM_PLANE_PIXEL_SOURCE_FB) |
+ BIT(DRM_PLANE_PIXEL_SOURCE_NONE);
+ int i;
+
+ /* FB is supported by default */
+ unsigned long supported_sources = extra_sources |
+ BIT(DRM_PLANE_PIXEL_SOURCE_FB) |
+ BIT(DRM_PLANE_PIXEL_SOURCE_NONE);
+
+ if (WARN_ON(supported_sources & ~valid_source_mask))
+ return -EINVAL;
+
+ prop = drm_property_create(dev, DRM_MODE_PROP_ENUM | DRM_MODE_PROP_ATOMIC, "pixel_source",
+ hweight32(supported_sources));
+
+ if (!prop)
+ return -ENOMEM;
+
+ for (i = 0; i < ARRAY_SIZE(drm_pixel_source_enum_list); i++) {
+ int ret;
+
+ if (!test_bit(drm_pixel_source_enum_list[i].type, &supported_sources))
+ continue;
+
+ ret = drm_property_add_enum(prop, drm_pixel_source_enum_list[i].type,
+ drm_pixel_source_enum_list[i].name);
+ if (ret) {
+ drm_property_destroy(dev, prop);
+
+ return ret;
+ }
+ }
+
+ drm_object_attach_property(&plane->base, prop, DRM_PLANE_PIXEL_SOURCE_FB);
+ plane->pixel_source_property = prop;
+
+ return 0;
+}
+EXPORT_SYMBOL(drm_plane_create_pixel_source_property);
diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index 24e7998d1731..559d101162ba 100644
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -839,6 +839,14 @@ bool drm_any_plane_has_format(struct drm_device *dev,
}
EXPORT_SYMBOL(drm_any_plane_has_format);

+static bool drm_plane_needs_disable(struct drm_plane_state *state, struct drm_framebuffer *fb)
+{
+ if (state->pixel_source == DRM_PLANE_PIXEL_SOURCE_NONE)
+ return true;
+
+ return state->pixel_source == DRM_PLANE_PIXEL_SOURCE_FB && fb == NULL;
+}
+
/*
* __setplane_internal - setplane handler for internal callers
*
@@ -861,8 +869,8 @@ static int __setplane_internal(struct drm_plane *plane,

WARN_ON(drm_drv_uses_atomic_modeset(plane->dev));

- /* No fb means shut it down */
- if (!fb) {
+ /* No visible data means shut it down */
+ if (drm_plane_needs_disable(plane->state, fb)) {
plane->old_fb = plane->fb;
ret = plane->funcs->disable_plane(plane, ctx);
if (!ret) {
@@ -913,8 +921,8 @@ static int __setplane_atomic(struct drm_plane *plane,

WARN_ON(!drm_drv_uses_atomic_modeset(plane->dev));

- /* No fb means shut it down */
- if (!fb)
+ /* No visible data means shut it down */
+ if (drm_plane_needs_disable(plane->state, fb))
return plane->funcs->disable_plane(plane, ctx);

/*
@@ -987,6 +995,9 @@ int drm_mode_setplane(struct drm_device *dev, void *data,
return -ENOENT;
}

+ if (plane->state)
+ plane->state->pixel_source = DRM_PLANE_PIXEL_SOURCE_FB;
+
if (plane_req->fb_id) {
fb = drm_framebuffer_lookup(dev, file_priv, plane_req->fb_id);
if (!fb) {
diff --git a/include/drm/drm_blend.h b/include/drm/drm_blend.h
index 88bdfec3bd88..122bbfbaae33 100644
--- a/include/drm/drm_blend.h
+++ b/include/drm/drm_blend.h
@@ -58,4 +58,6 @@ int drm_atomic_normalize_zpos(struct drm_device *dev,
struct drm_atomic_state *state);
int drm_plane_create_blend_mode_property(struct drm_plane *plane,
unsigned int supported_modes);
+int drm_plane_create_pixel_source_property(struct drm_plane *plane,
+ unsigned long extra_sources);
#endif
diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
index 51291983ea44..89508b4dea4a 100644
--- a/include/drm/drm_plane.h
+++ b/include/drm/drm_plane.h
@@ -40,6 +40,12 @@ enum drm_scaling_filter {
DRM_SCALING_FILTER_NEAREST_NEIGHBOR,
};

+enum drm_plane_pixel_source {
+ DRM_PLANE_PIXEL_SOURCE_NONE,
+ DRM_PLANE_PIXEL_SOURCE_FB,
+ DRM_PLANE_PIXEL_SOURCE_MAX
+};
+
/**
* struct drm_plane_state - mutable plane state
*
@@ -116,6 +122,14 @@ struct drm_plane_state {
/** @src_h: height of visible portion of plane (in 16.16) */
uint32_t src_h, src_w;

+ /**
+ * @pixel_source:
+ *
+ * Source of pixel information for the plane. See
+ * drm_plane_create_pixel_source_property() for more details.
+ */
+ enum drm_plane_pixel_source pixel_source;
+
/**
* @alpha:
* Opacity of the plane with 0 as completely transparent and 0xffff as
@@ -699,6 +713,13 @@ struct drm_plane {
*/
struct drm_plane_state *state;

+ /*
+ * @pixel_source_property:
+ * Optional pixel_source property for this plane. See
+ * drm_plane_create_pixel_source_property().
+ */
+ struct drm_property *pixel_source_property;
+
/**
* @alpha_property:
* Optional alpha property for this plane. See

--
2.42.0