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XenevaOS
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#include <drm_mode.h>
struct drm_mode_get_connector - Get connector metadata.
User-space can perform a GETCONNECTOR ioctl to retrieve information about a connector. User-space is expected to retrieve encoders, modes and properties by performing this ioctl at least twice: the first time to retrieve the number of elements, the second time to retrieve the elements themselves.
To retrieve the number of elements, set @count_props and @count_encoders to zero, set @count_modes to 1, and set @modes_ptr to a temporary struct drm_mode_modeinfo element.
To retrieve the elements, allocate arrays for @encoders_ptr, @modes_ptr, @props_ptr and @prop_values_ptr, then set @count_modes, @count_props and @count_encoders to their capacity.
Performing the ioctl only twice may be racy: the number of elements may have changed with a hotplug event in-between the two ioctls. User-space is expected to retry the last ioctl until the number of elements stabilizes. The kernel won't fill any array which doesn't have the expected length.
Force-probing a connector
If the @count_modes field is set to zero and the DRM client is the current DRM master, the kernel will perform a forced probe on the connector to refresh the connector status, modes and EDID. A forced-probe can be slow, might cause flickering and the ioctl will block.
User-space needs to force-probe connectors to ensure their metadata is up-to-date at startup and after receiving a hot-plug event. User-space may perform a forced-probe when the user explicitly requests it. User-space shouldn't perform a forced-probe in other situations.
| __u32 drm_mode_get_connector::connection |
@connection: Status of the connector.
See enum drm_connector_status.
| __u32 drm_mode_get_connector::connector_id |
@connector_id: Object ID of the connector.
| __u32 drm_mode_get_connector::connector_type |
@connector_type: Type of the connector.
See DRM_MODE_CONNECTOR_* defines.
| __u32 drm_mode_get_connector::connector_type_id |
@connector_type_id: Type-specific connector number.
This is not an object ID. This is a per-type connector number. Each (type, type_id) combination is unique across all connectors of a DRM device.
The (type, type_id) combination is not a stable identifier: the type_id can change depending on the driver probe order.
| __u32 drm_mode_get_connector::count_encoders |
@count_encoders: Number of encoders.
| __u32 drm_mode_get_connector::count_modes |
@count_modes: Number of modes.
| __u32 drm_mode_get_connector::count_props |
@count_props: Number of properties.
| __u32 drm_mode_get_connector::encoder_id |
@encoder_id: Object ID of the current encoder.
| __u64 drm_mode_get_connector::encoders_ptr |
@encoders_ptr: Pointer to __u32 array of object IDs.
| __u32 drm_mode_get_connector::mm_height |
@mm_height: Height of the connected sink in millimeters.
| __u32 drm_mode_get_connector::mm_width |
@mm_width: Width of the connected sink in millimeters.
| __u64 drm_mode_get_connector::modes_ptr |
@modes_ptr: Pointer to struct drm_mode_modeinfo array.
| __u32 drm_mode_get_connector::pad |
@pad: Padding, must be zero.
| __u64 drm_mode_get_connector::prop_values_ptr |
@prop_values_ptr: Pointer to __u64 array of property values.
| __u64 drm_mode_get_connector::props_ptr |
@props_ptr: Pointer to __u32 array of property IDs.
| __u32 drm_mode_get_connector::subpixel |
@subpixel: Subpixel order of the connected sink.
See enum subpixel_order.
1.9.8