mirror of https://gitee.com/openkylin/linux.git
378 lines
11 KiB
ReStructuredText
378 lines
11 KiB
ReStructuredText
=========================
|
|
Kernel Mode Setting (KMS)
|
|
=========================
|
|
|
|
Drivers must initialize the mode setting core by calling
|
|
:c:func:`drm_mode_config_init()` on the DRM device. The function
|
|
initializes the :c:type:`struct drm_device <drm_device>`
|
|
mode_config field and never fails. Once done, mode configuration must
|
|
be setup by initializing the following fields.
|
|
|
|
- int min_width, min_height; int max_width, max_height;
|
|
Minimum and maximum width and height of the frame buffers in pixel
|
|
units.
|
|
|
|
- struct drm_mode_config_funcs \*funcs;
|
|
Mode setting functions.
|
|
|
|
Mode Configuration
|
|
|
|
KMS Core Structures and Functions
|
|
=================================
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_mode_config.c
|
|
:export:
|
|
|
|
.. kernel-doc:: include/drm/drm_mode_config.h
|
|
:internal:
|
|
|
|
Modeset Base Object Abstraction
|
|
===============================
|
|
|
|
.. kernel-doc:: include/drm/drm_mode_object.h
|
|
:internal:
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_mode_object.c
|
|
:export:
|
|
|
|
Atomic Mode Setting Function Reference
|
|
======================================
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_atomic.c
|
|
:export:
|
|
|
|
.. kernel-doc:: include/drm/drm_atomic.h
|
|
:internal:
|
|
|
|
CRTC Abstraction
|
|
================
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_crtc.c
|
|
:export:
|
|
|
|
.. kernel-doc:: include/drm/drm_crtc.h
|
|
:internal:
|
|
|
|
Frame Buffer Abstraction
|
|
========================
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_framebuffer.c
|
|
:doc: overview
|
|
|
|
Frame Buffer Functions Reference
|
|
--------------------------------
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_framebuffer.c
|
|
:export:
|
|
|
|
.. kernel-doc:: include/drm/drm_framebuffer.h
|
|
:internal:
|
|
|
|
DRM Format Handling
|
|
===================
|
|
|
|
.. kernel-doc:: include/drm/drm_fourcc.h
|
|
:internal:
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_fourcc.c
|
|
:export:
|
|
|
|
Dumb Buffer Objects
|
|
===================
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_dumb_buffers.c
|
|
:doc: overview
|
|
|
|
Plane Abstraction
|
|
=================
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_plane.c
|
|
:doc: overview
|
|
|
|
Plane Functions Reference
|
|
-------------------------
|
|
|
|
.. kernel-doc:: include/drm/drm_plane.h
|
|
:internal:
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_plane.c
|
|
:export:
|
|
|
|
Display Modes Function Reference
|
|
================================
|
|
|
|
.. kernel-doc:: include/drm/drm_modes.h
|
|
:internal:
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_modes.c
|
|
:export:
|
|
|
|
Connector Abstraction
|
|
=====================
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_connector.c
|
|
:doc: overview
|
|
|
|
Connector Functions Reference
|
|
-----------------------------
|
|
|
|
.. kernel-doc:: include/drm/drm_connector.h
|
|
:internal:
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_connector.c
|
|
:export:
|
|
|
|
Encoder Abstraction
|
|
===================
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_encoder.c
|
|
:doc: overview
|
|
|
|
Encoder Functions Reference
|
|
---------------------------
|
|
|
|
.. kernel-doc:: include/drm/drm_encoder.h
|
|
:internal:
|
|
|
|
.. 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_mode_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
|
|
===========
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_modeset_lock.c
|
|
:doc: kms locking
|
|
|
|
.. kernel-doc:: include/drm/drm_modeset_lock.h
|
|
:internal:
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_modeset_lock.c
|
|
:export:
|
|
|
|
KMS Properties
|
|
==============
|
|
|
|
Property Types and Blob Property Support
|
|
----------------------------------------
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_property.c
|
|
:doc: overview
|
|
|
|
.. kernel-doc:: include/drm/drm_property.h
|
|
:internal:
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_property.c
|
|
:export:
|
|
|
|
Standard Connector Properties
|
|
-----------------------------
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_connector.c
|
|
:doc: standard connector properties
|
|
|
|
Plane Composition Properties
|
|
----------------------------
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_blend.c
|
|
:doc: overview
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_blend.c
|
|
:export:
|
|
|
|
Color Management Properties
|
|
---------------------------
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_color_mgmt.c
|
|
:doc: overview
|
|
|
|
.. kernel-doc:: include/drm/drm_color_mgmt.h
|
|
:internal:
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_color_mgmt.c
|
|
:export:
|
|
|
|
Tile Group Property
|
|
-------------------
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_connector.c
|
|
:doc: Tile group
|
|
|
|
Explicit Fencing Properties
|
|
---------------------------
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_atomic.c
|
|
:doc: explicit fencing properties
|
|
|
|
Existing KMS Properties
|
|
-----------------------
|
|
|
|
The following table gives description of drm properties exposed by
|
|
various modules/drivers.
|
|
|
|
.. csv-table::
|
|
:header-rows: 1
|
|
:file: kms-properties.csv
|
|
|
|
Vertical Blanking
|
|
=================
|
|
|
|
Vertical blanking plays a major role in graphics rendering. To achieve
|
|
tear-free display, users must synchronize page flips and/or rendering to
|
|
vertical blanking. The DRM API offers ioctls to perform page flips
|
|
synchronized to vertical blanking and wait for vertical blanking.
|
|
|
|
The DRM core handles most of the vertical blanking management logic,
|
|
which involves filtering out spurious interrupts, keeping race-free
|
|
blanking counters, coping with counter wrap-around and resets and
|
|
keeping use counts. It relies on the driver to generate vertical
|
|
blanking interrupts and optionally provide a hardware vertical blanking
|
|
counter. Drivers must implement the following operations.
|
|
|
|
- int (\*enable_vblank) (struct drm_device \*dev, int crtc); void
|
|
(\*disable_vblank) (struct drm_device \*dev, int crtc);
|
|
Enable or disable vertical blanking interrupts for the given CRTC.
|
|
|
|
- u32 (\*get_vblank_counter) (struct drm_device \*dev, int crtc);
|
|
Retrieve the value of the vertical blanking counter for the given
|
|
CRTC. If the hardware maintains a vertical blanking counter its value
|
|
should be returned. Otherwise drivers can use the
|
|
:c:func:`drm_vblank_count()` helper function to handle this
|
|
operation.
|
|
|
|
Drivers must initialize the vertical blanking handling core with a call
|
|
to :c:func:`drm_vblank_init()` in their load operation.
|
|
|
|
Vertical blanking interrupts can be enabled by the DRM core or by
|
|
drivers themselves (for instance to handle page flipping operations).
|
|
The DRM core maintains a vertical blanking use count to ensure that the
|
|
interrupts are not disabled while a user still needs them. To increment
|
|
the use count, drivers call :c:func:`drm_vblank_get()`. Upon
|
|
return vertical blanking interrupts are guaranteed to be enabled.
|
|
|
|
To decrement the use count drivers call
|
|
:c:func:`drm_vblank_put()`. Only when the use count drops to zero
|
|
will the DRM core disable the vertical blanking interrupts after a delay
|
|
by scheduling a timer. The delay is accessible through the
|
|
vblankoffdelay module parameter or the ``drm_vblank_offdelay`` global
|
|
variable and expressed in milliseconds. Its default value is 5000 ms.
|
|
Zero means never disable, and a negative value means disable
|
|
immediately. Drivers may override the behaviour by setting the
|
|
:c:type:`struct drm_device <drm_device>`
|
|
vblank_disable_immediate flag, which when set causes vblank interrupts
|
|
to be disabled immediately regardless of the drm_vblank_offdelay
|
|
value. The flag should only be set if there's a properly working
|
|
hardware vblank counter present.
|
|
|
|
When a vertical blanking interrupt occurs drivers only need to call the
|
|
:c:func:`drm_handle_vblank()` function to account for the
|
|
interrupt.
|
|
|
|
Resources allocated by :c:func:`drm_vblank_init()` must be freed
|
|
with a call to :c:func:`drm_vblank_cleanup()` in the driver unload
|
|
operation handler.
|
|
|
|
Vertical Blanking and Interrupt Handling Functions Reference
|
|
------------------------------------------------------------
|
|
|
|
.. kernel-doc:: drivers/gpu/drm/drm_irq.c
|
|
:export:
|
|
|
|
.. kernel-doc:: include/drm/drm_irq.h
|
|
:internal:
|