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author | Daniel Vetter <daniel.vetter@ffwll.ch> | 2019-01-30 19:30:05 +0300 |
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committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2019-01-31 00:16:18 +0300 |
commit | d9f7bb56c2925ea0641fe5121b954acc6a873605 (patch) | |
tree | 9be56fb11558379fb33fae2aa01fd8c5b788ad07 /Documentation/gpu | |
parent | 5d0aa37855635ac99bcebcaf559e6d9d867e72f9 (diff) | |
download | linux-d9f7bb56c2925ea0641fe5121b954acc6a873605.tar.xz |
drm/doc: Drop chapter "KMS Initialization and Cleanup"
It only talks about crtc, brings up intel as an example and I think is
more misleading than useful really. Plus we have lots of discussion
about how your standard kms driver should be initialized/cleaned up,
so maybe better to document this when we have a better idea.
v2: Fix typo in commit message (Nicholas).
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190130163006.28945-2-daniel.vetter@ffwll.ch
Diffstat (limited to 'Documentation/gpu')
-rw-r--r-- | Documentation/gpu/drm-kms.rst | 96 |
1 files changed, 0 insertions, 96 deletions
diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst index 75c882e09fee..23a3c986ef6d 100644 --- a/Documentation/gpu/drm-kms.rst +++ b/Documentation/gpu/drm-kms.rst @@ -410,102 +410,6 @@ Encoder Functions Reference .. kernel-doc:: drivers/gpu/drm/drm_encoder.c :export: -KMS Initialization and Cleanup -============================== - -A KMS device is abstracted and exposed as a set of planes, CRTCs, -encoders and connectors. KMS drivers must thus create and initialize all -those objects at load time after initializing mode setting. - -CRTCs (:c:type:`struct drm_crtc <drm_crtc>`) --------------------------------------------- - -A CRTC is an abstraction representing a part of the chip that contains a -pointer to a scanout buffer. Therefore, the number of CRTCs available -determines how many independent scanout buffers can be active at any -given time. The CRTC structure contains several fields to support this: -a pointer to some video memory (abstracted as a frame buffer object), a -display mode, and an (x, y) offset into the video memory to support -panning or configurations where one piece of video memory spans multiple -CRTCs. - -CRTC Initialization -~~~~~~~~~~~~~~~~~~~ - -A KMS device must create and register at least one struct -:c:type:`struct drm_crtc <drm_crtc>` instance. The instance is -allocated and zeroed by the driver, possibly as part of a larger -structure, and registered with a call to :c:func:`drm_crtc_init()` -with a pointer to CRTC functions. - - -Cleanup -------- - -The DRM core manages its objects' lifetime. When an object is not needed -anymore the core calls its destroy function, which must clean up and -free every resource allocated for the object. Every -:c:func:`drm_\*_init()` call must be matched with a corresponding -:c:func:`drm_\*_cleanup()` call to cleanup CRTCs -(:c:func:`drm_crtc_cleanup()`), planes -(:c:func:`drm_plane_cleanup()`), encoders -(:c:func:`drm_encoder_cleanup()`) and connectors -(:c:func:`drm_connector_cleanup()`). Furthermore, connectors that -have been added to sysfs must be removed by a call to -:c:func:`drm_connector_unregister()` before calling -:c:func:`drm_connector_cleanup()`. - -Connectors state change detection must be cleanup up with a call to -:c:func:`drm_kms_helper_poll_fini()`. - -Output discovery and initialization example -------------------------------------------- - -.. code-block:: c - - void intel_crt_init(struct drm_device *dev) - { - struct drm_connector *connector; - struct intel_output *intel_output; - - intel_output = kzalloc(sizeof(struct intel_output), GFP_KERNEL); - if (!intel_output) - return; - - connector = &intel_output->base; - drm_connector_init(dev, &intel_output->base, - &intel_crt_connector_funcs, DRM_MODE_CONNECTOR_VGA); - - drm_encoder_init(dev, &intel_output->enc, &intel_crt_enc_funcs, - DRM_MODE_ENCODER_DAC); - - drm_connector_attach_encoder(&intel_output->base, - &intel_output->enc); - - /* Set up the DDC bus. */ - intel_output->ddc_bus = intel_i2c_create(dev, GPIOA, "CRTDDC_A"); - if (!intel_output->ddc_bus) { - dev_printk(KERN_ERR, &dev->pdev->dev, "DDC bus registration " - "failed.\n"); - return; - } - - intel_output->type = INTEL_OUTPUT_ANALOG; - connector->interlace_allowed = 0; - connector->doublescan_allowed = 0; - - drm_encoder_helper_add(&intel_output->enc, &intel_crt_helper_funcs); - drm_connector_helper_add(connector, &intel_crt_connector_helper_funcs); - - drm_connector_register(connector); - } - -In the example above (taken from the i915 driver), a CRTC, connector and -encoder combination is created. A device-specific i2c bus is also -created for fetching EDID data and performing monitor detection. Once -the process is complete, the new connector is registered with sysfs to -make its properties available to applications. - KMS Locking =========== |