diff options
| -rw-r--r-- | Documentation/gpu/drm-kms.rst | 46 | ||||
| -rw-r--r-- | drivers/gpu/drm/drm_encoder.c | 48 | ||||
| -rw-r--r-- | include/drm/drm_encoder.h | 70 |
3 files changed, 101 insertions, 63 deletions
diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst index 7f788caebea3..47c2835b7c2d 100644 --- a/Documentation/gpu/drm-kms.rst +++ b/Documentation/gpu/drm-kms.rst @@ -128,6 +128,12 @@ Connector Functions Reference Encoder Abstraction =================== +.. kernel-doc:: drivers/gpu/drm/drm_encoder.c + :doc: overview + +Encoder Functions Reference +--------------------------- + .. kernel-doc:: include/drm/drm_encoder.h :internal: @@ -207,46 +213,6 @@ future); drivers that do not wish to provide special handling for primary planes may make use of the helper functions described in ? to create and register a primary plane with standard capabilities. -Encoders (:c:type:`struct drm_encoder <drm_encoder>`) ------------------------------------------------------ - -An encoder takes pixel data from a CRTC and converts it to a format -suitable for any attached connectors. On some devices, it may be -possible to have a CRTC send data to more than one encoder. In that -case, both encoders would receive data from the same scanout buffer, -resulting in a "cloned" display configuration across the connectors -attached to each encoder. - -Encoder Initialization -~~~~~~~~~~~~~~~~~~~~~~ - -As for CRTCs, a KMS driver must create, initialize and register at least -one :c:type:`struct drm_encoder <drm_encoder>` instance. The -instance is allocated and zeroed by the driver, possibly as part of a -larger structure. - -Drivers must initialize the :c:type:`struct drm_encoder -<drm_encoder>` possible_crtcs and possible_clones fields before -registering the encoder. Both fields are bitmasks of respectively the -CRTCs that the encoder can be connected to, and sibling encoders -candidate for cloning. - -After being initialized, the encoder must be registered with a call to -:c:func:`drm_encoder_init()`. The function takes a pointer to the -encoder functions and an encoder type. Supported types are - -- DRM_MODE_ENCODER_DAC for VGA and analog on DVI-I/DVI-A -- DRM_MODE_ENCODER_TMDS for DVI, HDMI and (embedded) DisplayPort -- DRM_MODE_ENCODER_LVDS for display panels -- DRM_MODE_ENCODER_TVDAC for TV output (Composite, S-Video, - Component, SCART) -- DRM_MODE_ENCODER_VIRTUAL for virtual machine displays - -Encoders must be attached to a CRTC to be used. DRM drivers leave -encoders unattached at initialization time. Applications (or the fbdev -compatibility layer when implemented) are responsible for attaching the -encoders they want to use to a CRTC. - Cleanup ------- diff --git a/drivers/gpu/drm/drm_encoder.c b/drivers/gpu/drm/drm_encoder.c index bce781b7bb5f..998a6743a586 100644 --- a/drivers/gpu/drm/drm_encoder.c +++ b/drivers/gpu/drm/drm_encoder.c @@ -26,6 +26,30 @@ #include "drm_crtc_internal.h" +/** + * DOC: overview + * + * Encoders represent the connecting element between the CRTC (as the overall + * pixel pipeline, represented by struct &drm_crtc) and the connectors (as the + * generic sink entity, represented by struct &drm_connector). Encoders are + * objects exposed to userspace, originally to allow userspace to infer cloning + * and connector/CRTC restrictions. Unfortunately almost all drivers get this + * wrong, making the uabi pretty much useless. On top of that the exposed + * restrictions are too simple for todays hardware, and the recommend way to + * infer restrictions is by using the DRM_MODE_ATOMIC_TEST_ONLY flag for the + * atomic IOCTL. + * + * Otherwise encoders aren't used in the uapi at all (any modeset request from + * userspace directly connects a connector with a CRTC), drivers are therefore + * free to use them however they wish. Modeset helper libraries make strong use + * of encoders to facilitate code sharing. But for more complex settings it is + * usually better to move shared code into a separate &drm_bridge. Compared to + * encoders bridges also have the benefit of not being purely an internal + * abstraction since they are not exposed to userspace at all. + * + * Encoders are initialized with drm_encoder_init() and cleaned up using + * drm_encoder_cleanup(). + */ static const struct drm_prop_enum_list drm_encoder_enum_list[] = { { DRM_MODE_ENCODER_NONE, "None" }, { DRM_MODE_ENCODER_DAC, "DAC" }, @@ -71,16 +95,17 @@ void drm_encoder_unregister_all(struct drm_device *dev) * @encoder_type: user visible type of the encoder * @name: printf style format string for the encoder name, or NULL for default name * - * Initialises a preallocated encoder. Encoder should be - * subclassed as part of driver encoder objects. + * Initialises a preallocated encoder. Encoder should be subclassed as part of + * driver encoder objects. At driver unload time drm_encoder_cleanup() should be + * called from the driver's destroy hook in &drm_encoder_funcs. * * Returns: * Zero on success, error code on failure. */ int drm_encoder_init(struct drm_device *dev, - struct drm_encoder *encoder, - const struct drm_encoder_funcs *funcs, - int encoder_type, const char *name, ...) + struct drm_encoder *encoder, + const struct drm_encoder_funcs *funcs, + int encoder_type, const char *name, ...) { int ret; @@ -176,19 +201,6 @@ static struct drm_crtc *drm_encoder_get_crtc(struct drm_encoder *encoder) return encoder->crtc; } -/** - * drm_mode_getencoder - get encoder configuration - * @dev: drm device for the ioctl - * @data: data pointer for the ioctl - * @file_priv: drm file for the ioctl call - * - * Construct a encoder configuration structure to return to the user. - * - * Called by the user via ioctl. - * - * Returns: - * Zero on success, negative errno on failure. - */ int drm_mode_getencoder(struct drm_device *dev, void *data, struct drm_file *file_priv) { diff --git a/include/drm/drm_encoder.h b/include/drm/drm_encoder.h index 2712fd1a686b..3d7350f1fcc1 100644 --- a/include/drm/drm_encoder.h +++ b/include/drm/drm_encoder.h @@ -84,9 +84,6 @@ struct drm_encoder_funcs { * @head: list management * @base: base KMS object * @name: human readable name, can be overwritten by the driver - * @encoder_type: one of the DRM_MODE_ENCODER_<foo> types in drm_mode.h - * @possible_crtcs: bitmask of potential CRTC bindings - * @possible_clones: bitmask of potential sibling encoders for cloning * @crtc: currently bound CRTC * @bridge: bridge associated to the encoder * @funcs: control functions @@ -101,6 +98,32 @@ struct drm_encoder { struct drm_mode_object base; char *name; + /** + * @encoder_type: + * + * One of the DRM_MODE_ENCODER_<foo> types in drm_mode.h. The following + * encoder types are defined thus far: + * + * - DRM_MODE_ENCODER_DAC for VGA and analog on DVI-I/DVI-A. + * + * - DRM_MODE_ENCODER_TMDS for DVI, HDMI and (embedded) DisplayPort. + * + * - DRM_MODE_ENCODER_LVDS for display panels, or in general any panel + * with a proprietary parallel connector. + * + * - DRM_MODE_ENCODER_TVDAC for TV output (Composite, S-Video, + * Component, SCART). + * + * - DRM_MODE_ENCODER_VIRTUAL for virtual machine displays + * + * - DRM_MODE_ENCODER_DSI for panels connected using the DSI serial bus. + * + * - DRM_MODE_ENCODER_DPI for panels connected using the DPI parallel + * bus. + * + * - DRM_MODE_ENCODER_DPMST for special fake encoders used to allow + * mutliple DP MST streams to share one physical encoder. + */ int encoder_type; /** @@ -109,7 +132,34 @@ struct drm_encoder { */ unsigned index; + /** + * @possible_crtcs: Bitmask of potential CRTC bindings, using + * drm_crtc_index() as the index into the bitfield. The driver must set + * the bits for all &drm_crtc objects this encoder can be connected to + * before calling drm_encoder_init(). + * + * In reality almost every driver gets this wrong. + * + * Note that since CRTC objects can't be hotplugged the assigned indices + * are stable and hence known before registering all objects. + */ uint32_t possible_crtcs; + + /** + * @possible_clones: Bitmask of potential sibling encoders for cloning, + * using drm_encoder_index() as the index into the bitfield. The driver + * must set the bits for all &drm_encoder objects which can clone a + * &drm_crtc together with this encoder before calling + * drm_encoder_init(). Drivers should set the bit representing the + * encoder itself, too. Cloning bits should be set such that when two + * encoders can be used in a cloned configuration, they both should have + * each another bits set. + * + * In reality almost every driver gets this wrong. + * + * Note that since encoder objects can't be hotplugged the assigned indices + * are stable and hence known before registering all objects. + */ uint32_t possible_clones; struct drm_crtc *crtc; @@ -146,7 +196,7 @@ static inline uint32_t drm_crtc_mask(struct drm_crtc *crtc); * @encoder: encoder to test * @crtc: crtc to test * - * Return false if @encoder can't be driven by @crtc, true otherwise. + * Returns false if @encoder can't be driven by @crtc, true otherwise. */ static inline bool drm_encoder_crtc_ok(struct drm_encoder *encoder, struct drm_crtc *crtc) @@ -154,11 +204,21 @@ static inline bool drm_encoder_crtc_ok(struct drm_encoder *encoder, return !!(encoder->possible_crtcs & drm_crtc_mask(crtc)); } +/** + * drm_encoder_find - find a &drm_encoder + * @dev: DRM device + * @id: encoder id + * + * Returns the encoder with @id, NULL if it doesn't exist. Simple wrapper around + * drm_mode_object_find(). + */ static inline struct drm_encoder *drm_encoder_find(struct drm_device *dev, - uint32_t id) + uint32_t id) { struct drm_mode_object *mo; + mo = drm_mode_object_find(dev, id, DRM_MODE_OBJECT_ENCODER); + return mo ? obj_to_encoder(mo) : NULL; } |