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fix: don't assume 0x0000..0xFFFF as KMS plane alpha range #463

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merged 1 commit into from
Dec 10, 2024
Merged

fix: don't assume 0x0000..0xFFFF as KMS plane alpha range #463

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17 changes: 11 additions & 6 deletions src/modesetting.c
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Original file line number Diff line number Diff line change
Expand Up @@ -757,11 +757,16 @@ static int fetch_plane(int drm_fd, uint32_t plane_id, struct drm_plane *plane_ou
} else if (streq(info->name, "alpha")) {
has_alpha = true;
assert(info->flags == DRM_MODE_PROP_RANGE);
assert(info->values[0] == 0);
assert(info->values[1] == 0xFFFF);
assert(props->prop_values[j] <= 0xFFFF);

committed_alpha = (uint16_t) props->prop_values[j];
assert(info->values[0] <= 0xFFFF);
assert(info->values[1] <= 0xFFFF);
assert(info->values[0] <= info->values[1]);
plane_out->min_alpha = (uint16_t) info->values[0];
plane_out->max_alpha = (uint16_t) info->values[1];

uint64_t value = props->prop_values[j];
assert(plane_out->min_alpha <= value);
assert(value <= plane_out->max_alpha);
committed_alpha = (uint16_t) value;
} else if (streq(info->name, "pixel blend mode")) {
has_blend_mode = true;
assert(info->flags == DRM_MODE_PROP_ENUM);
Expand Down Expand Up @@ -2568,7 +2573,7 @@ int kms_req_builder_push_fb_layer(

if (index == 0) {
if (plane->has_alpha) {
drmModeAtomicAddProperty(builder->req, plane_id, plane->ids.alpha, DRM_BLEND_ALPHA_OPAQUE);
drmModeAtomicAddProperty(builder->req, plane_id, plane->ids.alpha, plane->max_alpha);
}

if (plane->has_blend_mode && plane->supported_blend_modes[kNone_DrmBlendMode]) {
Expand Down
41 changes: 23 additions & 18 deletions src/modesetting.h
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Original file line number Diff line number Diff line change
Expand Up @@ -215,8 +215,6 @@

#define DECLARE_PROP_ID_AS_UINT32(prop_name, prop_var_name) uint32_t prop_var_name;

#define DRM_BLEND_ALPHA_OPAQUE 0xFFFF

enum drm_blend_mode {
kPremultiplied_DrmBlendMode,
kCoverage_DrmBlendMode,
Expand Down Expand Up @@ -502,6 +500,13 @@ struct drm_plane {
/// @brief Whether this plane has a mutable alpha property we can set.
bool has_alpha;

/// @brief The minimum and maximum alpha values.
///
/// Only valid if @ref has_alpha is true.
///
/// This should be 0x0000..0xFFFF, but the xilinx driver uses different values.
uint16_t min_alpha, max_alpha;

/// @brief Whether this plane has a mutable pixel blend mode we can set.
bool has_blend_mode;

Expand Down Expand Up @@ -750,15 +755,15 @@ DECLARE_REF_OPS(kms_req_builder);

/**
* @brief Gets the @ref drmdev associated with this KMS request builder.
*
*
* @param builder The KMS request builder.
* @returns The drmdev associated with this KMS request builder.
*/
struct drmdev *kms_req_builder_get_drmdev(struct kms_req_builder *builder);

/**
* @brief Gets the CRTC associated with this KMS request builder.
*
*
* @param builder The KMS request builder.
* @returns The CRTC associated with this KMS request builder.
*/
Expand All @@ -768,7 +773,7 @@ struct drm_crtc *kms_req_builder_get_crtc(struct kms_req_builder *builder);
* @brief Adds a property to the KMS request that will set the given video mode
* on this CRTC on commit, regardless of whether the currently committed output
* mode is the same.
*
*
* @param builder The KMS request builder.
* @param mode The output mode to set (on @ref kms_req_commit)
* @returns Zero if successful, positive errno-style error on failure.
Expand All @@ -779,7 +784,7 @@ int kms_req_builder_set_mode(struct kms_req_builder *builder, const drmModeModeI
* @brief Adds a property to the KMS request that will unset the configured
* output mode for this CRTC on commit, regardless of whether the currently
* committed output mdoe is already unset.
*
*
* @param builder The KMS request builder.
* @returns Zero if successful, positive errno-style error on failure.
*/
Expand All @@ -788,7 +793,7 @@ int kms_req_builder_unset_mode(struct kms_req_builder *builder);
/**
* @brief Adds a property to the KMS request that will change the connector
* that this CRTC is displaying content on to @param connector_id.
*
*
* @param builder The KMS request builder.
* @param connector_id The connector that this CRTC should display contents on.
* @returns Zero if successful, EINVAL if the @param connector_id is invalid.
Expand All @@ -799,11 +804,11 @@ int kms_req_builder_set_connector(struct kms_req_builder *builder, uint32_t conn
* @brief True if the next layer pushed using @ref kms_req_builder_push_fb_layer
* should be opaque, i.e. use a framebuffer which has a pixel format that has no
* alpha channel.
*
*
* This is true for the bottom-most layer. There are some display controllers
* that don't support non-opaque pixel formats for the bottom-most (primary)
* plane. So ignoring this might lead to an EINVAL on commit.
*
*
* @param builder The KMS request builder.
* @returns True if the next layer should preferably be opaque, false if there's
* no preference.
Expand All @@ -812,30 +817,30 @@ bool kms_req_builder_prefer_next_layer_opaque(struct kms_req_builder *builder);

/**
* @brief Adds a new framebuffer (display) layer on top of the last layer.
*
*
* If this is the first layer, the framebuffer should cover the entire screen
* (CRTC).
*
*
* To allow the use of explicit fencing, specify an in_fence_fd in @param layer
* and a @param deferred_release_callback.
*
*
* If explicit fencing is supported:
* - the in_fence_fd should be a DRM syncobj fd that signals
* when the GPU has finished rendering to the framebuffer and is ready
* to be scanned out.
* - @param deferred_release_callback will be called
* with a DRM syncobj fd that is signaled once the framebuffer is no longer
* being displayed on screen (and can be rendered into again)
*
*
* If explicit fencing is not supported:
* - the in_fence_fd in @param layer will be closed by this procedure.
* - @param deferred_release_callback will NOT be called and
* @param release_callback will be called instead.
*
*
* Explicit fencing is supported: When atomic modesetting is being used and
* the driver supports it. (Driver has IN_FENCE_FD plane and OUT_FENCE_PTR crtc
* properties)
*
*
* @param builder The KMS request builder.
* @param layer The exact details (src pos, output pos, rotation,
* framebuffer) of the layer that should be shown on
Expand Down Expand Up @@ -878,7 +883,7 @@ int kms_req_builder_push_fb_layer(
/**
* @brief Push a "fake" layer that just keeps one zpos free, incase something
* other than KMS wants to display contents there. (e.g. omxplayer)
*
*
* @param builder The KMS request builder.
* @param zpos_out Filled with the zpos that won't be occupied by the request
* builder.
Expand All @@ -889,7 +894,7 @@ int kms_req_builder_push_zpos_placeholder_layer(struct kms_req_builder *builder,
/**
* @brief A KMS request (atomic or legacy modesetting) that can be committed to
* change the state of a single CRTC.
*
*
* Only way to construct this is by building a KMS request using
* @ref kms_req_builder and then calling @ref kms_req_builder_build.
*/
Expand All @@ -900,7 +905,7 @@ DECLARE_REF_OPS(kms_req);
/**
* @brief Build the KMS request builder into an actual, immutable KMS request
* that can be committed. Internally this doesn't do much at all.
*
*
* @param builder The KMS request builder that should be built.
* @returns KMS request that can be committed using @ref kms_req_commit_blocking
* or @ref kms_req_commit_nonblocking.
Expand Down
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