drm/doc: Document the KMS property API
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> Reviewed-by: Alex Deucher <alexander.deucher@amd.com> Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Laurent Pinchart
Dave Airlie
parent
02c030a718
commit
421cda3e32
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@ -1235,6 +1235,15 @@ int max_width, max_height;</synopsis>
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<sect4>
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<title>Miscellaneous</title>
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<itemizedlist>
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<listitem>
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<synopsis>void (*set_property)(struct drm_crtc *crtc,
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struct drm_property *property, uint64_t value);</synopsis>
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<para>
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Set the value of the given CRTC property to
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<parameter>value</parameter>. See <xref linkend="drm-kms-properties"/>
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for more information about properties.
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</para>
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</listitem>
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<listitem>
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<synopsis>void (*gamma_set)(struct drm_crtc *crtc, u16 *r, u16 *g, u16 *b,
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uint32_t start, uint32_t size);</synopsis>
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@ -1385,6 +1394,15 @@ int max_width, max_height;</synopsis>
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<xref linkend="drm-kms-init"/>.
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</para>
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</listitem>
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<listitem>
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<synopsis>void (*set_property)(struct drm_plane *plane,
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struct drm_property *property, uint64_t value);</synopsis>
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<para>
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Set the value of the given plane property to
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<parameter>value</parameter>. See <xref linkend="drm-kms-properties"/>
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for more information about properties.
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</para>
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</listitem>
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</itemizedlist>
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</sect3>
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</sect2>
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@ -1593,6 +1611,15 @@ int max_width, max_height;</synopsis>
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<sect4>
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<title>Miscellaneous</title>
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<itemizedlist>
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<listitem>
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<synopsis>void (*set_property)(struct drm_connector *connector,
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struct drm_property *property, uint64_t value);</synopsis>
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<para>
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Set the value of the given connector property to
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<parameter>value</parameter>. See <xref linkend="drm-kms-properties"/>
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for more information about properties.
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</para>
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</listitem>
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<listitem>
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<synopsis>void (*destroy)(struct drm_connector *connector);</synopsis>
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<para>
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@ -2187,6 +2214,122 @@ void intel_crt_init(struct drm_device *dev)
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</sect2>
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</sect1>
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<!-- Internals: kms properties -->
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<sect1 id="drm-kms-properties">
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<title>KMS Properties</title>
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<para>
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Drivers may need to expose additional parameters to applications than
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those described in the previous sections. KMS supports attaching
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properties to CRTCs, connectors and planes and offers a userspace API to
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list, get and set the property values.
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</para>
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<para>
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Properties are identified by a name that uniquely defines the property
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purpose, and store an associated value. For all property types except blob
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properties the value is a 64-bit unsigned integer.
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</para>
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<para>
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KMS differentiates between properties and property instances. Drivers
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first create properties and then create and associate individual instances
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of those properties to objects. A property can be instantiated multiple
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times and associated with different objects. Values are stored in property
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instances, and all other property information are stored in the propery
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and shared between all instances of the property.
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</para>
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<para>
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Every property is created with a type that influences how the KMS core
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handles the property. Supported property types are
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<variablelist>
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<varlistentry>
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<term>DRM_MODE_PROP_RANGE</term>
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<listitem><para>Range properties report their minimum and maximum
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admissible values. The KMS core verifies that values set by
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application fit in that range.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term>DRM_MODE_PROP_ENUM</term>
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<listitem><para>Enumerated properties take a numerical value that
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ranges from 0 to the number of enumerated values defined by the
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property minus one, and associate a free-formed string name to each
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value. Applications can retrieve the list of defined value-name pairs
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and use the numerical value to get and set property instance values.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term>DRM_MODE_PROP_BITMASK</term>
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<listitem><para>Bitmask properties are enumeration properties that
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additionally restrict all enumerated values to the 0..63 range.
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Bitmask property instance values combine one or more of the
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enumerated bits defined by the property.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term>DRM_MODE_PROP_BLOB</term>
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<listitem><para>Blob properties store a binary blob without any format
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restriction. The binary blobs are created as KMS standalone objects,
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and blob property instance values store the ID of their associated
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blob object.</para>
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<para>Blob properties are only used for the connector EDID property
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and cannot be created by drivers.</para></listitem>
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</varlistentry>
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</variablelist>
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</para>
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<para>
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To create a property drivers call one of the following functions depending
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on the property type. All property creation functions take property flags
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and name, as well as type-specific arguments.
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<itemizedlist>
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<listitem>
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<synopsis>struct drm_property *drm_property_create_range(struct drm_device *dev, int flags,
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const char *name,
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uint64_t min, uint64_t max);</synopsis>
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<para>Create a range property with the given minimum and maximum
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values.</para>
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</listitem>
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<listitem>
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<synopsis>struct drm_property *drm_property_create_enum(struct drm_device *dev, int flags,
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const char *name,
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const struct drm_prop_enum_list *props,
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int num_values);</synopsis>
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<para>Create an enumerated property. The <parameter>props</parameter>
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argument points to an array of <parameter>num_values</parameter>
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value-name pairs.</para>
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</listitem>
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<listitem>
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<synopsis>struct drm_property *drm_property_create_bitmask(struct drm_device *dev,
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int flags, const char *name,
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const struct drm_prop_enum_list *props,
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int num_values);</synopsis>
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<para>Create a bitmask property. The <parameter>props</parameter>
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argument points to an array of <parameter>num_values</parameter>
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value-name pairs.</para>
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</listitem>
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</itemizedlist>
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</para>
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<para>
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Properties can additionally be created as immutable, in which case they
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will be read-only for applications but can be modified by the driver. To
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create an immutable property drivers must set the DRM_MODE_PROP_IMMUTABLE
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flag at property creation time.
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</para>
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<para>
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When no array of value-name pairs is readily available at property
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creation time for enumerated or range properties, drivers can create
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the property using the <function>drm_property_create</function> function
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and manually add enumeration value-name pairs by calling the
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<function>drm_property_add_enum</function> function. Care must be taken to
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properly specify the property type through the <parameter>flags</parameter>
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argument.
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</para>
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<para>
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After creating properties drivers can attach property instances to CRTC,
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connector and plane objects by calling the
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<function>drm_object_attach_property</function>. The function takes a
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pointer to the target object, a pointer to the previously created property
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and an initial instance value.
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</para>
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</sect1>
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<!-- Internals: vertical blanking -->
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<sect1 id="drm-vertical-blank">
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