Merge tag 'topic/drm-misc-2016-06-22-updated' of...

	    genericirq.xml s390-drivers.xml uio-howto.xml scsi.xml \

	    80211.xml debugobjects.xml sh.xml regulator.xml \

	    alsa-driver-api.xml writing-an-alsa-driver.xml \

	    tracepoint.xml gpu.xml media_api.xml w1.xml \

	    tracepoint.xml media_api.xml w1.xml \

	    writing_musb_glue_layer.xml crypto-API.xml iio.xml

include Documentation/DocBook/media/Makefile

=============

DRM Internals

=============

This chapter documents DRM internals relevant to driver authors and

developers working to add support for the latest features to existing

drivers.

First, we go over some typical driver initialization requirements, like

setting up command buffers, creating an initial output configuration,

and initializing core services. Subsequent sections cover core internals

in more detail, providing implementation notes and examples.

The DRM layer provides several services to graphics drivers, many of

them driven by the application interfaces it provides through libdrm,

the library that wraps most of the DRM ioctls. These include vblank

event handling, memory management, output management, framebuffer

management, command submission & fencing, suspend/resume support, and

DMA services.

Driver Initialization

=====================

At the core of every DRM driver is a :c:type:`struct drm_driver

<drm_driver>` structure. Drivers typically statically initialize

a drm_driver structure, and then pass it to

:c:func:`drm_dev_alloc()` to allocate a device instance. After the

device instance is fully initialized it can be registered (which makes

it accessible from userspace) using :c:func:`drm_dev_register()`.

The :c:type:`struct drm_driver <drm_driver>` structure

contains static information that describes the driver and features it

supports, and pointers to methods that the DRM core will call to

implement the DRM API. We will first go through the :c:type:`struct

drm_driver <drm_driver>` static information fields, and will

then describe individual operations in details as they get used in later

sections.

Driver Information

------------------

Driver Features

~~~~~~~~~~~~~~~

Drivers inform the DRM core about their requirements and supported

features by setting appropriate flags in the driver_features field.

Since those flags influence the DRM core behaviour since registration

time, most of them must be set to registering the :c:type:`struct

drm_driver <drm_driver>` instance.

u32 driver_features;

DRIVER_USE_AGP

    Driver uses AGP interface, the DRM core will manage AGP resources.

DRIVER_REQUIRE_AGP

    Driver needs AGP interface to function. AGP initialization failure

    will become a fatal error.

DRIVER_PCI_DMA

    Driver is capable of PCI DMA, mapping of PCI DMA buffers to

    userspace will be enabled. Deprecated.

DRIVER_SG

    Driver can perform scatter/gather DMA, allocation and mapping of

    scatter/gather buffers will be enabled. Deprecated.

DRIVER_HAVE_DMA

    Driver supports DMA, the userspace DMA API will be supported.

    Deprecated.

DRIVER_HAVE_IRQ; DRIVER_IRQ_SHARED

    DRIVER_HAVE_IRQ indicates whether the driver has an IRQ handler

    managed by the DRM Core. The core will support simple IRQ handler

    installation when the flag is set. The installation process is

    described in ?.

    DRIVER_IRQ_SHARED indicates whether the device & handler support

    shared IRQs (note that this is required of PCI drivers).

DRIVER_GEM

    Driver use the GEM memory manager.

DRIVER_MODESET

    Driver supports mode setting interfaces (KMS).

DRIVER_PRIME

    Driver implements DRM PRIME buffer sharing.

DRIVER_RENDER

    Driver supports dedicated render nodes.

DRIVER_ATOMIC

    Driver supports atomic properties. In this case the driver must

    implement appropriate obj->atomic_get_property() vfuncs for any

    modeset objects with driver specific properties.

Major, Minor and Patchlevel

~~~~~~~~~~~~~~~~~~~~~~~~~~~

int major; int minor; int patchlevel;

The DRM core identifies driver versions by a major, minor and patch

level triplet. The information is printed to the kernel log at

initialization time and passed to userspace through the

DRM_IOCTL_VERSION ioctl.

The major and minor numbers are also used to verify the requested driver

API version passed to DRM_IOCTL_SET_VERSION. When the driver API

changes between minor versions, applications can call

DRM_IOCTL_SET_VERSION to select a specific version of the API. If the

requested major isn't equal to the driver major, or the requested minor

is larger than the driver minor, the DRM_IOCTL_SET_VERSION call will

return an error. Otherwise the driver's set_version() method will be

called with the requested version.

Name, Description and Date

~~~~~~~~~~~~~~~~~~~~~~~~~~

char \*name; char \*desc; char \*date;

The driver name is printed to the kernel log at initialization time,

used for IRQ registration and passed to userspace through

DRM_IOCTL_VERSION.

The driver description is a purely informative string passed to

userspace through the DRM_IOCTL_VERSION ioctl and otherwise unused by

the kernel.

The driver date, formatted as YYYYMMDD, is meant to identify the date of

the latest modification to the driver. However, as most drivers fail to

update it, its value is mostly useless. The DRM core prints it to the

kernel log at initialization time and passes it to userspace through the

DRM_IOCTL_VERSION ioctl.

Device Instance and Driver Handling

-----------------------------------

.. kernel-doc:: drivers/gpu/drm/drm_drv.c

   :doc: driver instance overview

.. kernel-doc:: drivers/gpu/drm/drm_drv.c

   :export:

Driver Load

-----------

IRQ Registration

~~~~~~~~~~~~~~~~

The DRM core tries to facilitate IRQ handler registration and

unregistration by providing :c:func:`drm_irq_install()` and

:c:func:`drm_irq_uninstall()` functions. Those functions only

support a single interrupt per device, devices that use more than one

IRQs need to be handled manually.

Managed IRQ Registration

''''''''''''''''''''''''

:c:func:`drm_irq_install()` starts by calling the irq_preinstall

driver operation. The operation is optional and must make sure that the

interrupt will not get fired by clearing all pending interrupt flags or

disabling the interrupt.

The passed-in IRQ will then be requested by a call to

:c:func:`request_irq()`. If the DRIVER_IRQ_SHARED driver feature

flag is set, a shared (IRQF_SHARED) IRQ handler will be requested.

The IRQ handler function must be provided as the mandatory irq_handler

driver operation. It will get passed directly to

:c:func:`request_irq()` and thus has the same prototype as all IRQ

handlers. It will get called with a pointer to the DRM device as the

second argument.

Finally the function calls the optional irq_postinstall driver

operation. The operation usually enables interrupts (excluding the

vblank interrupt, which is enabled separately), but drivers may choose

to enable/disable interrupts at a different time.

:c:func:`drm_irq_uninstall()` is similarly used to uninstall an

IRQ handler. It starts by waking up all processes waiting on a vblank

interrupt to make sure they don't hang, and then calls the optional

irq_uninstall driver operation. The operation must disable all hardware

interrupts. Finally the function frees the IRQ by calling

:c:func:`free_irq()`.

Manual IRQ Registration

'''''''''''''''''''''''

Drivers that require multiple interrupt handlers can't use the managed

IRQ registration functions. In that case IRQs must be registered and

unregistered manually (usually with the :c:func:`request_irq()` and

:c:func:`free_irq()` functions, or their devm_\* equivalent).

When manually registering IRQs, drivers must not set the

DRIVER_HAVE_IRQ driver feature flag, and must not provide the

irq_handler driver operation. They must set the :c:type:`struct

drm_device <drm_device>` irq_enabled field to 1 upon

registration of the IRQs, and clear it to 0 after unregistering the

IRQs.

Memory Manager Initialization

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Every DRM driver requires a memory manager which must be initialized at

load time. DRM currently contains two memory managers, the Translation

Table Manager (TTM) and the Graphics Execution Manager (GEM). This

document describes the use of the GEM memory manager only. See ? for

details.

Miscellaneous Device Configuration

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Another task that may be necessary for PCI devices during configuration

is mapping the video BIOS. On many devices, the VBIOS describes device

configuration, LCD panel timings (if any), and contains flags indicating

device state. Mapping the BIOS can be done using the pci_map_rom()

call, a convenience function that takes care of mapping the actual ROM,

whether it has been shadowed into memory (typically at address 0xc0000)

or exists on the PCI device in the ROM BAR. Note that after the ROM has

been mapped and any necessary information has been extracted, it should

be unmapped; on many devices, the ROM address decoder is shared with

other BARs, so leaving it mapped could cause undesired behaviour like

hangs or memory corruption.

Bus-specific Device Registration and PCI Support

------------------------------------------------

A number of functions are provided to help with device registration. The

functions deal with PCI and platform devices respectively and are only

provided for historical reasons. These are all deprecated and shouldn't

be used in new drivers. Besides that there's a few helpers for pci

drivers.

.. kernel-doc:: drivers/gpu/drm/drm_pci.c

   :export:

.. kernel-doc:: drivers/gpu/drm/drm_platform.c

   :export:

Open/Close, File Operations and IOCTLs

======================================

Open and Close

--------------

int (\*firstopen) (struct drm_device \*); void (\*lastclose) (struct

drm_device \*); int (\*open) (struct drm_device \*, struct drm_file

\*); void (\*preclose) (struct drm_device \*, struct drm_file \*);

void (\*postclose) (struct drm_device \*, struct drm_file \*);

    Open and close handlers. None of those methods are mandatory.

The firstopen method is called by the DRM core for legacy UMS (User Mode

Setting) drivers only when an application opens a device that has no

other opened file handle. UMS drivers can implement it to acquire device

resources. KMS drivers can't use the method and must acquire resources

in the load method instead.

Similarly the lastclose method is called when the last application

holding a file handle opened on the device closes it, for both UMS and

KMS drivers. Additionally, the method is also called at module unload

time or, for hot-pluggable devices, when the device is unplugged. The

firstopen and lastclose calls can thus be unbalanced.

The open method is called every time the device is opened by an

application. Drivers can allocate per-file private data in this method

and store them in the struct :c:type:`struct drm_file

<drm_file>` driver_priv field. Note that the open method is

called before firstopen.

The close operation is split into preclose and postclose methods.

Drivers must stop and cleanup all per-file operations in the preclose

method. For instance pending vertical blanking and page flip events must

be cancelled. No per-file operation is allowed on the file handle after

returning from the preclose method.

Finally the postclose method is called as the last step of the close

operation, right before calling the lastclose method if no other open

file handle exists for the device. Drivers that have allocated per-file

private data in the open method should free it here.

The lastclose method should restore CRTC and plane properties to default

value, so that a subsequent open of the device will not inherit state

from the previous user. It can also be used to execute delayed power

switching state changes, e.g. in conjunction with the vga_switcheroo

infrastructure (see ?). Beyond that KMS drivers should not do any

further cleanup. Only legacy UMS drivers might need to clean up device

state so that the vga console or an independent fbdev driver could take

over.

File Operations

---------------

.. kernel-doc:: drivers/gpu/drm/drm_fops.c

   :doc: file operations

.. kernel-doc:: drivers/gpu/drm/drm_fops.c

   :export:

IOCTLs

------

struct drm_ioctl_desc \*ioctls; int num_ioctls;

    Driver-specific ioctls descriptors table.

Driver-specific ioctls numbers start at DRM_COMMAND_BASE. The ioctls

descriptors table is indexed by the ioctl number offset from the base

value. Drivers can use the DRM_IOCTL_DEF_DRV() macro to initialize

the table entries.

::

    DRM_IOCTL_DEF_DRV(ioctl, func, flags)

``ioctl`` is the ioctl name. Drivers must define the DRM_##ioctl and

DRM_IOCTL_##ioctl macros to the ioctl number offset from

DRM_COMMAND_BASE and the ioctl number respectively. The first macro is

private to the device while the second must be exposed to userspace in a

public header.

``func`` is a pointer to the ioctl handler function compatible with the

``drm_ioctl_t`` type.

::

    typedef int drm_ioctl_t(struct drm_device *dev, void *data,

            struct drm_file *file_priv);

``flags`` is a bitmask combination of the following values. It restricts

how the ioctl is allowed to be called.

-  DRM_AUTH - Only authenticated callers allowed

-  DRM_MASTER - The ioctl can only be called on the master file handle

-  DRM_ROOT_ONLY - Only callers with the SYSADMIN capability allowed

-  DRM_CONTROL_ALLOW - The ioctl can only be called on a control

   device

-  DRM_UNLOCKED - The ioctl handler will be called without locking the

   DRM global mutex. This is the enforced default for kms drivers (i.e.

   using the DRIVER_MODESET flag) and hence shouldn't be used any more

   for new drivers.

.. kernel-doc:: drivers/gpu/drm/drm_ioctl.c

   :export:

Legacy Support Code

===================

The section very briefly covers some of the old legacy support code

which is only used by old DRM drivers which have done a so-called

shadow-attach to the underlying device instead of registering as a real

driver. This also includes some of the old generic buffer management and

command submission code. Do not use any of this in new and modern

drivers.

Legacy Suspend/Resume

---------------------

The DRM core provides some suspend/resume code, but drivers wanting full

suspend/resume support should provide save() and restore() functions.

These are called at suspend, hibernate, or resume time, and should

perform any state save or restore required by your device across suspend

or hibernate states.

int (\*suspend) (struct drm_device \*, pm_message_t state); int

(\*resume) (struct drm_device \*);

Those are legacy suspend and resume methods which *only* work with the

legacy shadow-attach driver registration functions. New driver should

use the power management interface provided by their bus type (usually

through the :c:type:`struct device_driver <device_driver>`

dev_pm_ops) and set these methods to NULL.

Legacy DMA Services

-------------------

This should cover how DMA mapping etc. is supported by the core. These

functions are deprecated and should not be used.

=============================

Mode Setting Helper Functions

=============================

The plane, CRTC, encoder and connector functions provided by the drivers

implement the DRM API. They're called by the DRM core and ioctl handlers

to handle device state changes and configuration request. As

implementing those functions often requires logic not specific to

drivers, mid-layer helper functions are available to avoid duplicating

boilerplate code.

The DRM core contains one mid-layer implementation. The mid-layer

provides implementations of several plane, CRTC, encoder and connector

functions (called from the top of the mid-layer) that pre-process

requests and call lower-level functions provided by the driver (at the

bottom of the mid-layer). For instance, the

:c:func:`drm_crtc_helper_set_config()` function can be used to

fill the :c:type:`struct drm_crtc_funcs <drm_crtc_funcs>`

set_config field. When called, it will split the set_config operation

in smaller, simpler operations and call the driver to handle them.

To use the mid-layer, drivers call

:c:func:`drm_crtc_helper_add()`,

:c:func:`drm_encoder_helper_add()` and

:c:func:`drm_connector_helper_add()` functions to install their

mid-layer bottom operations handlers, and fill the :c:type:`struct

drm_crtc_funcs <drm_crtc_funcs>`, :c:type:`struct

drm_encoder_funcs <drm_encoder_funcs>` and :c:type:`struct

drm_connector_funcs <drm_connector_funcs>` structures with

pointers to the mid-layer top API functions. Installing the mid-layer

bottom operation handlers is best done right after registering the

corresponding KMS object.

The mid-layer is not split between CRTC, encoder and connector

operations. To use it, a driver must provide bottom functions for all of

the three KMS entities.

Atomic Modeset Helper Functions Reference

=========================================

Overview

--------

.. kernel-doc:: drivers/gpu/drm/drm_atomic_helper.c

   :doc: overview

Implementing Asynchronous Atomic Commit

---------------------------------------

.. kernel-doc:: drivers/gpu/drm/drm_atomic_helper.c

   :doc: implementing nonblocking commit

Atomic State Reset and Initialization

-------------------------------------

.. kernel-doc:: drivers/gpu/drm/drm_atomic_helper.c

   :doc: atomic state reset and initialization

.. kernel-doc:: include/drm/drm_atomic_helper.h

   :internal:

.. kernel-doc:: drivers/gpu/drm/drm_atomic_helper.c

   :export:

Modeset Helper Reference for Common Vtables

===========================================

.. kernel-doc:: include/drm/drm_modeset_helper_vtables.h

   :internal:

.. kernel-doc:: include/drm/drm_modeset_helper_vtables.h

   :doc: overview

Legacy CRTC/Modeset Helper Functions Reference

==============================================

.. kernel-doc:: drivers/gpu/drm/drm_crtc_helper.c

   :export:

.. kernel-doc:: drivers/gpu/drm/drm_crtc_helper.c

   :doc: overview

Output Probing Helper Functions Reference

=========================================

.. kernel-doc:: drivers/gpu/drm/drm_probe_helper.c

   :doc: output probing helper overview

.. kernel-doc:: drivers/gpu/drm/drm_probe_helper.c

   :export:

fbdev Helper Functions Reference

================================

.. kernel-doc:: drivers/gpu/drm/drm_fb_helper.c

   :doc: fbdev helpers

.. kernel-doc:: drivers/gpu/drm/drm_fb_helper.c

   :export:

.. kernel-doc:: include/drm/drm_fb_helper.h

   :internal:

Framebuffer CMA Helper Functions Reference

==========================================

.. kernel-doc:: drivers/gpu/drm/drm_fb_cma_helper.c

   :doc: framebuffer cma helper functions

.. kernel-doc:: drivers/gpu/drm/drm_fb_cma_helper.c

   :export:

Display Port Helper Functions Reference

=======================================

.. kernel-doc:: drivers/gpu/drm/drm_dp_helper.c

   :doc: dp helpers

.. kernel-doc:: include/drm/drm_dp_helper.h

   :internal:

.. kernel-doc:: drivers/gpu/drm/drm_dp_helper.c

   :export:

Display Port Dual Mode Adaptor Helper Functions Reference

=========================================================

.. kernel-doc:: drivers/gpu/drm/drm_dp_dual_mode_helper.c

   :doc: dp dual mode helpers

.. kernel-doc:: include/drm/drm_dp_dual_mode_helper.h

   :internal:

.. kernel-doc:: drivers/gpu/drm/drm_dp_dual_mode_helper.c

   :export:

Display Port MST Helper Functions Reference

===========================================

.. kernel-doc:: drivers/gpu/drm/drm_dp_mst_topology.c

   :doc: dp mst helper

.. kernel-doc:: include/drm/drm_dp_mst_helper.h

   :internal:

.. kernel-doc:: drivers/gpu/drm/drm_dp_mst_topology.c

   :export:

MIPI DSI Helper Functions Reference

===================================

.. kernel-doc:: drivers/gpu/drm/drm_mipi_dsi.c

   :doc: dsi helpers

.. kernel-doc:: include/drm/drm_mipi_dsi.h

   :internal:

.. kernel-doc:: drivers/gpu/drm/drm_mipi_dsi.c

   :export:

EDID Helper Functions Reference

===============================

.. kernel-doc:: drivers/gpu/drm/drm_edid.c

   :export:

Rectangle Utilities Reference

=============================

.. kernel-doc:: include/drm/drm_rect.h

   :doc: rect utils

.. kernel-doc:: include/drm/drm_rect.h

   :internal:

.. kernel-doc:: drivers/gpu/drm/drm_rect.c

   :export:

Flip-work Helper Reference

==========================

.. kernel-doc:: include/drm/drm_flip_work.h

   :doc: flip utils

.. kernel-doc:: include/drm/drm_flip_work.h

   :internal:

.. kernel-doc:: drivers/gpu/drm/drm_flip_work.c

   :export:

HDMI Infoframes Helper Reference

================================

Strictly speaking this is not a DRM helper library but generally useable

by any driver interfacing with HDMI outputs like v4l or alsa drivers.

But it nicely fits into the overall topic of mode setting helper

libraries and hence is also included here.

.. kernel-doc:: include/linux/hdmi.h

   :internal:

.. kernel-doc:: drivers/video/hdmi.c

   :export:

Plane Helper Reference

======================

.. kernel-doc:: drivers/gpu/drm/drm_plane_helper.c

   :export:

.. kernel-doc:: drivers/gpu/drm/drm_plane_helper.c

   :doc: overview

Tile group

----------

.. kernel-doc:: drivers/gpu/drm/drm_crtc.c

   :doc: Tile group

Bridges

=======

Overview

--------

.. kernel-doc:: drivers/gpu/drm/drm_bridge.c

   :doc: overview

Default bridge callback sequence

--------------------------------

.. kernel-doc:: drivers/gpu/drm/drm_bridge.c

   :doc: bridge callbacks

.. kernel-doc:: drivers/gpu/drm/drm_bridge.c

   :export:

Panel Helper Reference

======================

.. kernel-doc:: include/drm/drm_panel.h

   :internal:

.. kernel-doc:: drivers/gpu/drm/drm_panel.c

   :export:

.. kernel-doc:: drivers/gpu/drm/drm_panel.c

   :doc: drm panel

Simple KMS Helper Reference

===========================

.. kernel-doc:: include/drm/drm_simple_kms_helper.h

   :internal:

.. kernel-doc:: drivers/gpu/drm/drm_simple_kms_helper.c

   :export:

.. kernel-doc:: drivers/gpu/drm/drm_simple_kms_helper.c

   :doc: overview