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drm: Update connector documentation
- Shuffle docs from drm-kms.rst into the structure docs where it makes sense. - Put the remaining bits into a new overview section. One thing I've changed is around probing: Old docs says that you _must_ use the probe helpers, which isn't correct. Helpers are always optional. v2: Review from Sean. Cc: Sean Paul <seanpaul@chromium.org> Reviewed-by: Sean Paul <seanpaul@chromium.org> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1471034937-651-17-git-send-email-daniel.vetter@ffwll.ch
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Daniel Vetter
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@ -110,8 +110,14 @@ Display Modes Function Reference
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.. kernel-doc:: drivers/gpu/drm/drm_modes.c
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:export:
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Connector Display Sink Abstraction
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==================================
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Connector Abstraction
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=====================
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.. kernel-doc:: drivers/gpu/drm/drm_connector.c
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:doc: overview
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Connector Functions Reference
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-----------------------------
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.. kernel-doc:: include/drm/drm_connector.h
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:internal:
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@ -232,166 +238,6 @@ encoders unattached at initialization time. Applications (or the fbdev
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compatibility layer when implemented) are responsible for attaching the
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encoders they want to use to a CRTC.
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Connectors (:c:type:`struct drm_connector <drm_connector>`)
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-----------------------------------------------------------
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A connector is the final destination for pixel data on a device, and
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usually connects directly to an external display device like a monitor
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or laptop panel. A connector can only be attached to one encoder at a
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time. The connector is also the structure where information about the
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attached display is kept, so it contains fields for display data, EDID
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data, DPMS & connection status, and information about modes supported on
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the attached displays.
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Connector Initialization
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~~~~~~~~~~~~~~~~~~~~~~~~
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Finally a KMS driver must create, initialize, register and attach at
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least one :c:type:`struct drm_connector <drm_connector>`
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instance. The instance is created as other KMS objects and initialized
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by setting the following fields.
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interlace_allowed
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Whether the connector can handle interlaced modes.
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doublescan_allowed
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Whether the connector can handle doublescan.
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display_info
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Display information is filled from EDID information when a display
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is detected. For non hot-pluggable displays such as flat panels in
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embedded systems, the driver should initialize the
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display_info.width_mm and display_info.height_mm fields with the
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physical size of the display.
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polled
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Connector polling mode, a combination of
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DRM_CONNECTOR_POLL_HPD
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The connector generates hotplug events and doesn't need to be
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periodically polled. The CONNECT and DISCONNECT flags must not
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be set together with the HPD flag.
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DRM_CONNECTOR_POLL_CONNECT
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Periodically poll the connector for connection.
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DRM_CONNECTOR_POLL_DISCONNECT
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Periodically poll the connector for disconnection.
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Set to 0 for connectors that don't support connection status
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discovery.
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The connector is then registered with a call to
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:c:func:`drm_connector_init()` with a pointer to the connector
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functions and a connector type, and exposed through sysfs with a call to
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:c:func:`drm_connector_register()`.
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Supported connector types are
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- DRM_MODE_CONNECTOR_VGA
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- DRM_MODE_CONNECTOR_DVII
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- DRM_MODE_CONNECTOR_DVID
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- DRM_MODE_CONNECTOR_DVIA
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- DRM_MODE_CONNECTOR_Composite
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- DRM_MODE_CONNECTOR_SVIDEO
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- DRM_MODE_CONNECTOR_LVDS
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- DRM_MODE_CONNECTOR_Component
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- DRM_MODE_CONNECTOR_9PinDIN
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- DRM_MODE_CONNECTOR_DisplayPort
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- DRM_MODE_CONNECTOR_HDMIA
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- DRM_MODE_CONNECTOR_HDMIB
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- DRM_MODE_CONNECTOR_TV
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- DRM_MODE_CONNECTOR_eDP
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- DRM_MODE_CONNECTOR_VIRTUAL
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Connectors must be attached to an encoder to be used. For devices that
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map connectors to encoders 1:1, the connector should be attached at
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initialization time with a call to
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:c:func:`drm_mode_connector_attach_encoder()`. The driver must
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also set the :c:type:`struct drm_connector <drm_connector>`
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encoder field to point to the attached encoder.
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Finally, drivers must initialize the connectors state change detection
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with a call to :c:func:`drm_kms_helper_poll_init()`. If at least
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one connector is pollable but can't generate hotplug interrupts
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(indicated by the DRM_CONNECTOR_POLL_CONNECT and
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DRM_CONNECTOR_POLL_DISCONNECT connector flags), a delayed work will
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automatically be queued to periodically poll for changes. Connectors
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that can generate hotplug interrupts must be marked with the
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DRM_CONNECTOR_POLL_HPD flag instead, and their interrupt handler must
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call :c:func:`drm_helper_hpd_irq_event()`. The function will
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queue a delayed work to check the state of all connectors, but no
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periodic polling will be done.
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Connector Operations
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~~~~~~~~~~~~~~~~~~~~
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**Note**
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Unless otherwise state, all operations are mandatory.
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DPMS
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''''
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void (\*dpms)(struct drm_connector \*connector, int mode);
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The DPMS operation sets the power state of a connector. The mode
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argument is one of
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- DRM_MODE_DPMS_ON
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- DRM_MODE_DPMS_STANDBY
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- DRM_MODE_DPMS_SUSPEND
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- DRM_MODE_DPMS_OFF
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In all but DPMS_ON mode the encoder to which the connector is attached
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should put the display in low-power mode by driving its signals
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appropriately. If more than one connector is attached to the encoder
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care should be taken not to change the power state of other displays as
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a side effect. Low-power mode should be propagated to the encoders and
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CRTCs when all related connectors are put in low-power mode.
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Modes
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'''''
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int (\*fill_modes)(struct drm_connector \*connector, uint32_t
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max_width, uint32_t max_height);
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Fill the mode list with all supported modes for the connector. If the
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``max_width`` and ``max_height`` arguments are non-zero, the
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implementation must ignore all modes wider than ``max_width`` or higher
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than ``max_height``.
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The connector must also fill in this operation its display_info
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width_mm and height_mm fields with the connected display physical size
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in millimeters. The fields should be set to 0 if the value isn't known
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or is not applicable (for instance for projector devices).
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Connection Status
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'''''''''''''''''
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The connection status is updated through polling or hotplug events when
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supported (see ?). The status value is reported to userspace through
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ioctls and must not be used inside the driver, as it only gets
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initialized by a call to :c:func:`drm_mode_getconnector()` from
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userspace.
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enum drm_connector_status (\*detect)(struct drm_connector
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\*connector, bool force);
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Check to see if anything is attached to the connector. The ``force``
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parameter is set to false whilst polling or to true when checking the
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connector due to user request. ``force`` can be used by the driver to
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avoid expensive, destructive operations during automated probing.
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Return connector_status_connected if something is connected to the
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connector, connector_status_disconnected if nothing is connected and
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connector_status_unknown if the connection state isn't known.
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Drivers should only return connector_status_connected if the
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connection status has really been probed as connected. Connectors that
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can't detect the connection status, or failed connection status probes,
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should return connector_status_unknown.
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Cleanup
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-------
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@ -27,6 +27,37 @@
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#include "drm_crtc_internal.h"
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#include "drm_internal.h"
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/**
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* DOC: overview
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*
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* In DRM connectors are the general abstraction for display sinks, and include
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* als fixed panels or anything else that can display pixels in some form. As
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* opposed to all other KMS objects representing hardware (like CRTC, encoder or
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* plane abstractions) connectors can be hotplugged and unplugged at runtime.
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* Hence they are reference-counted using drm_connector_reference() and
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* drm_connector_unreference().
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*
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* KMS driver must create, initialize, register and attach at a struct
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* &drm_connector for each such sink. The instance is created as other KMS
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* objects and initialized by setting the following fields.
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*
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* The connector is then registered with a call to drm_connector_init() with a
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* pointer to the connector functions and a connector type, and exposed through
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* sysfs with a call to drm_connector_register().
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*
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* Connectors must be attached to an encoder to be used. For devices that map
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* connectors to encoders 1:1, the connector should be attached at
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* initialization time with a call to drm_mode_connector_attach_encoder(). The
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* driver must also set the struct &drm_connector encoder field to point to the
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* attached encoder.
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*
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* For connectors which are not fixed (like built-in panels) the driver needs to
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* support hotplug notifications. The simplest way to do that is by using the
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* probe helpers, see drm_kms_helper_poll_init() for connectors which don't have
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* hardware support for hotplug interrupts. Connectors with hardware hotplug
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* support can instead use e.g. drm_helper_hpd_irq_event().
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*/
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struct drm_conn_prop_enum_list {
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int type;
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const char *name;
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@ -77,7 +108,7 @@ void drm_connector_ida_destroy(void)
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* drm_connector_get_cmdline_mode - reads the user's cmdline mode
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* @connector: connector to quwery
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*
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* The kernel supports per-connector configration of its consoles through
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* The kernel supports per-connector configuration of its consoles through
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* use of the video= parameter. This function parses that option and
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* extracts the user's specified mode (or enable/disable status) for a
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* particular connector. This is typically only used during the early fbdev
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@ -42,9 +42,36 @@ enum drm_connector_force {
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DRM_FORCE_ON_DIGITAL, /* for DVI-I use digital connector */
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};
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/**
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* enum drm_connector_status - status for a &drm_connector
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*
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* This enum is used to track the connector status. There are no separate
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* #defines for the uapi!
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*/
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enum drm_connector_status {
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/**
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* @connector_status_connected: The connector is definitely connected to
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* a sink device, and can be enabled.
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*/
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connector_status_connected = 1,
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/**
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* @connector_status_disconnected: The connector isn't connected to a
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* sink device which can be autodetect. For digital outputs like DP or
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* HDMI (which can be realiable probed) this means there's really
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* nothing there. It is driver-dependent whether a connector with this
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* status can be lit up or not.
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*/
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connector_status_disconnected = 2,
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/**
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* @connector_status_unknown: The connector's status could not be
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* reliably detected. This happens when probing would either cause
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* flicker (like load-detection when the connector is in use), or when a
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* hardware resource isn't available (like when load-detection needs a
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* free CRTC). It should be possible to light up the connector with one
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* of the listed fallback modes. For default configuration userspace
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* should only try to light up connectors with unknown status when
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* there's not connector with @connector_status_connected.
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*/
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connector_status_unknown = 3,
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};
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@ -416,11 +443,9 @@ struct drm_cmdline_mode {
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* @modes: modes available on this connector (from fill_modes() + user)
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* @status: one of the drm_connector_status enums (connected, not, or unknown)
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* @probed_modes: list of modes derived directly from the display
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* @display_info: information about attached display (e.g. from EDID)
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* @funcs: connector control functions
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* @edid_blob_ptr: DRM property containing EDID if present
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* @properties: property tracking for this connector
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* @polled: a DRM_CONNECTOR_POLL_<foo> value for core driven polling
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* @dpms: current dpms state
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* @helper_private: mid-layer private data
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* @cmdline_mode: mode line parsed from the kernel cmdline for this connector
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@ -485,6 +510,13 @@ struct drm_connector {
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/* these are modes added by probing with DDC or the BIOS */
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struct list_head probed_modes;
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/**
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* @display_info: Display information is filled from EDID information
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* when a display is detected. For non hot-pluggable displays such as
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* flat panels in embedded systems, the driver should initialize the
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* display_info.width_mm and display_info.height_mm fields with the
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* physical size of the display.
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*/
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struct drm_display_info display_info;
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const struct drm_connector_funcs *funcs;
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@ -519,7 +551,26 @@ struct drm_connector {
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/* DACs should rarely do this without a lot of testing */
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#define DRM_CONNECTOR_POLL_DISCONNECT (1 << 2)
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uint8_t polled; /* DRM_CONNECTOR_POLL_* */
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/**
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* @polled:
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*
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* Connector polling mode, a combination of
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*
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* DRM_CONNECTOR_POLL_HPD
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* The connector generates hotplug events and doesn't need to be
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* periodically polled. The CONNECT and DISCONNECT flags must not
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* be set together with the HPD flag.
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*
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* DRM_CONNECTOR_POLL_CONNECT
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* Periodically poll the connector for connection.
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*
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* DRM_CONNECTOR_POLL_DISCONNECT
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* Periodically poll the connector for disconnection.
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*
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* Set to 0 for connectors that don't support connection status
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* discovery.
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*/
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uint8_t polled;
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/* requested DPMS state */
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int dpms;
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