Am 24.01.2014 17:58, schrieb Daniel Vetter:
Just two typos ('said' my spellchecker...;-)
Regards,
Dieter
> - This is _not_ a generic interface to create gem objects, but just an
> interface to make early boot services (like boot splash) with a
> generic KMS userspace driver possible. Hence it's better to move
> the documentation for this from the GEM section to the KMS section,
> next to the creation of framebuffer objects.
>
> - Make it really clear that the returned handle isn't necessarily a
> GEM object (it can also be e.g. a TTM handle when running on top of
> vmwgfx).
>
> - Add a paragraph to make it clear that this is just for unaccelarated
> userspace - gpu drivers need to have their own buffer object
> creation ioctl which is hardware specific.
>
> v2: Clarify that the documentation doesn't just apply to GEM-based
> drivers only but is now generally valid, as suggested by David.
>
> v3: Polish the intro sentence a bit and one s/objects/handles/ for
> clarification, both suggested by Laurent.
>
> v4: More text polish from Laurent's review.
>
> Cc: David Herrmann <dh.herrmann at gmail.com>
> Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> ---
> Documentation/DocBook/drm.tmpl | 131
> ++++++++++++++++++++++-------------------
> 1 file changed, 71 insertions(+), 60 deletions(-)
>
> diff --git a/Documentation/DocBook/drm.tmpl
> b/Documentation/DocBook/drm.tmpl
> index ed1d6d289022..67cfe184749c 100644
> --- a/Documentation/DocBook/drm.tmpl
> +++ b/Documentation/DocBook/drm.tmpl
> @@ -830,62 +830,6 @@ char *date;</synopsis>
> </para>
> </sect3>
> <sect3>
> - <title>Dumb GEM Objects</title>
> - <para>
> - The GEM API doesn't standardize GEM objects creation and
> leaves it to
> - driver-specific ioctls. While not an issue for full-fledged
> graphics
> - stacks that include device-specific userspace components
> (in libdrm for
> - instance), this limit makes DRM-based early boot graphics
> unnecessarily
> - complex.
> - </para>
> - <para>
> - Dumb GEM objects partly alleviate the problem by providing a
> standard
> - API to create dumb buffers suitable for scanout, which can
> then be used
> - to create KMS frame buffers.
> - </para>
> - <para>
> - To support dumb GEM objects drivers must implement the
> - <methodname>dumb_create</methodname>,
> - <methodname>dumb_destroy</methodname> and
> - <methodname>dumb_map_offset</methodname> operations.
> - </para>
> - <itemizedlist>
> - <listitem>
> - <synopsis>int (*dumb_create)(struct drm_file *file_priv,
> struct drm_device *dev,
> - struct drm_mode_create_dumb *args);</synopsis>
> - <para>
> - The <methodname>dumb_create</methodname> operation
> creates a GEM
> - object suitable for scanout based on the width, height
> and depth
> - from the struct
> <structname>drm_mode_create_dumb</structname>
> - argument. It fills the argument's
> <structfield>handle</structfield>,
> - <structfield>pitch</structfield> and
> <structfield>size</structfield>
> - fields with a handle for the newly created GEM object
> and its line
> - pitch and size in bytes.
> - </para>
> - </listitem>
> - <listitem>
> - <synopsis>int (*dumb_destroy)(struct drm_file *file_priv,
> struct drm_device *dev,
> - uint32_t handle);</synopsis>
> - <para>
> - The <methodname>dumb_destroy</methodname> operation
> destroys a dumb
> - GEM object created by
> <methodname>dumb_create</methodname>.
> - </para>
> - </listitem>
> - <listitem>
> - <synopsis>int (*dumb_map_offset)(struct drm_file
> *file_priv, struct drm_device *dev,
> - uint32_t handle, uint64_t
> *offset);</synopsis>
> - <para>
> - The <methodname>dumb_map_offset</methodname> operation
> associates an
> - mmap fake offset with the GEM object given by the
> handle and returns
> - it. Drivers must use the
> - <function>drm_gem_create_mmap_offset</function> function
> to
> - associate the fake offset as described in
> - <xref linkend="drm-gem-objects-mapping"/>.
> - </para>
> - </listitem>
> - </itemizedlist>
> - </sect3>
> - <sect3>
> <title>Memory Coherency</title>
> <para>
> When mapped to the device or used in a command buffer,
> backing pages
> @@ -968,9 +912,11 @@ int max_width, max_height;</synopsis>
> Frame buffers rely on the underneath memory manager for
> low-level memory
> operations. When creating a frame buffer applications pass a
> memory
> handle (or a list of memory handles for multi-planar formats)
> through
> - the <parameter>drm_mode_fb_cmd2</parameter> argument. This
> document
> - assumes that the driver uses GEM, those handles thus reference
> GEM
> - objects.
> + the <parameter>drm_mode_fb_cmd2</parameter> argument. For drivers
> using
> + GEM as their userspace buffer management interface this would be a
> GEM
> + handle. Drivers are however free to use their own backing storage
> object
> + handles, e.g. vmwgfx directly exposes special TTM handles to
> userspace
> + and so expects TTM handles in the create ioctl and not GEM handles.
> </para>
> <para>
> Drivers must first validate the requested frame buffer
> parameters passed
> @@ -992,7 +938,7 @@ int max_width, max_height;</synopsis>
> </para>
>
> <para>
> - The initailization of the new framebuffer instance is finalized with
> a
> + The initilization of the new framebuffer instance is finalized with a
=> initialization ;-)
> call to <function>drm_framebuffer_init</function> which takes a
> pointer
> to DRM frame buffer operations (struct
> <structname>drm_framebuffer_funcs</structname>). Note that this
> function
> @@ -1052,6 +998,71 @@ int max_width, max_height;</synopsis>
> <function>drm_framebuffer_unregister_private</function>.
> </sect2>
> <sect2>
> + <title>Dumb Buffer Objects</title>
> + <para>
> + The KMS API doesn't standardize backing storage object creation and
> + leaves it to driver-specific ioctls. Furthermore actually creating a
> + buffer object even for GEM-based drivers is done through a
> + driver-specific ioctl - GEM only has a common userspace interface for
> + sharing and destroying objects. While not an issue for full-fledged
> + graphics stacks that include device-specific userspace components (in
> + libdrm for instance), this limit makes DRM-based early boot graphics
> + unnecessarily complex.
> + </para>
> + <para>
> + Dumb objects partly alleviate the problem by providing a
> standard
> + API to create dumb buffers suitable for scanout, which can
> then be used
> + to create KMS frame buffers.
> + </para>
> + <para>
> + To support dumb objects drivers must implement the
> + <methodname>dumb_create</methodname>,
> + <methodname>dumb_destroy</methodname> and
> + <methodname>dumb_map_offset</methodname> operations.
> + </para>
> + <itemizedlist>
> + <listitem>
> + <synopsis>int (*dumb_create)(struct drm_file *file_priv,
> struct drm_device *dev,
> + struct drm_mode_create_dumb *args);</synopsis>
> + <para>
> + The <methodname>dumb_create</methodname> operation creates
> a driver
> + object (GEM or TTM handle) suitable for scanout based on the
> + width, height and depth from the struct
> + <structname>drm_mode_create_dumb</structname> argument. It fills
> the
> + argument's <structfield>handle</structfield>,
> + <structfield>pitch</structfield> and
> <structfield>size</structfield>
> + fields with a handle for the newly created object and its line
> + pitch and size in bytes.
> + </para>
> + </listitem>
> + <listitem>
> + <synopsis>int (*dumb_destroy)(struct drm_file *file_priv,
> struct drm_device *dev,
> + uint32_t handle);</synopsis>
> + <para>
> + The <methodname>dumb_destroy</methodname> operation
> destroys a dumb
> + object created by <methodname>dumb_create</methodname>.
> + </para>
> + </listitem>
> + <listitem>
> + <synopsis>int (*dumb_map_offset)(struct drm_file
> *file_priv, struct drm_device *dev,
> + uint32_t handle, uint64_t *offset);</synopsis>
> + <para>
> + The <methodname>dumb_map_offset</methodname> operation
> associates an
> + mmap fake offset with the object given by the handle and
> returns
> + it. Drivers must use the
> + <function>drm_gem_create_mmap_offset</function> function
> to
> + associate the fake offset as described in
> + <xref linkend="drm-gem-objects-mapping"/>.
> + </para>
> + </listitem>
> + </itemizedlist>
> + <para>
> + Note that dumb objects may not be used for gpu accelaration,
=> acceleration
> as has been
> + attempted on some ARM embedded platforms. Such drivers really must
> have
> + a hardware-specific ioctl to allocate suitable buffer objects.
> + </para>
> + </sect2>
> + <sect2>
> <title>Output Polling</title>
> <synopsis>void (*output_poll_changed)(struct drm_device
> *dev);</synopsis>
> <para>
