// SPDX-License-Identifier: GPL-2.0-or-later
#include <linux/dma-resv.h>
#include <linux/dma-fence-chain.h>
#include <drm/drm_atomic_state_helper.h>
#include <drm/drm_atomic_uapi.h>
#include <drm/drm_framebuffer.h>
#include <drm/drm_gem.h>
#include <drm/drm_gem_atomic_helper.h>
#include <drm/drm_gem_framebuffer_helper.h>
#include <drm/drm_simple_kms_helper.h>
#include "drm_internal.h"
/**
* DOC: overview
*
* The GEM atomic helpers library implements generic atomic-commit
* functions for drivers that use GEM objects. Currently, it provides
* synchronization helpers, and plane state and framebuffer BO mappings
* for planes with shadow buffers.
*
* Before scanout, a plane's framebuffer needs to be synchronized with
* possible writers that draw into the framebuffer. All drivers should
* call drm_gem_plane_helper_prepare_fb() from their implementation of
* struct &drm_plane_helper.prepare_fb . It sets the plane's fence from
* the framebuffer so that the DRM core can synchronize access automatically.
* drm_gem_plane_helper_prepare_fb() can also be used directly as
* implementation of prepare_fb.
*
* .. code-block:: c
*
* #include <drm/drm_gem_atomic_helper.h>
*
* struct drm_plane_helper_funcs driver_plane_helper_funcs = {
* ...,
* . prepare_fb = drm_gem_plane_helper_prepare_fb,
* };
*
* A driver using a shadow buffer copies the content of the shadow buffers
* into the HW's framebuffer memory during an atomic update. This requires
* a mapping of the shadow buffer into kernel address space. The mappings
* cannot be established by commit-tail functions, such as atomic_update,
* as this would violate locking rules around dma_buf_vmap().
*
* The helpers for shadow-buffered planes establish and release mappings,
* and provide struct drm_shadow_plane_state, which stores the plane's mapping
* for commit-tail functions.
*
* Shadow-buffered planes can easily be enabled by using the provided macros
* %DRM_GEM_SHADOW_PLANE_FUNCS and %DRM_GEM_SHADOW_PLANE_HELPER_FUNCS.
* These macros set up the plane and plane-helper callbacks to point to the
* shadow-buffer helpers.
*
* .. code-block:: c
*
* #include <drm/drm_gem_atomic_helper.h>
*
* struct drm_plane_funcs driver_plane_funcs = {
* ...,
* DRM_GEM_SHADOW_PLANE_FUNCS,
* };
*
* struct drm_plane_helper_funcs driver_plane_helper_funcs = {
* ...,
* DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
* };
*
* In the driver's atomic-update function, shadow-buffer mappings are available
* from the plane state. Use to_drm_shadow_plane_state() to upcast from
* struct drm_plane_state.
*
* .. code-block:: c
*
* void driver_plane_atomic_update(struct drm_plane *plane,
* struct drm_plane_state *old_plane_state)
* {
* struct drm_plane_state *plane_state = plane->state;
* struct drm_shadow_plane_state *shadow_plane_state =
* to_drm_shadow_plane_state(plane_state);
*
* // access shadow buffer via shadow_plane_state->map
* }
*
* A mapping address for each of the framebuffer's buffer object is stored in
* struct &drm_shadow_plane_state.map. The mappings are valid while the state
* is being used.
*
* Drivers that use struct drm_simple_display_pipe can use
* %DRM_GEM_SIMPLE_DISPLAY_PIPE_SHADOW_PLANE_FUNCS to initialize the rsp
* callbacks. Access to shadow-buffer mappings is similar to regular
* atomic_update.
*
* .. code-block:: c
*
* struct drm_simple_display_pipe_funcs driver_pipe_funcs = {
* ...,
* DRM_GEM_SIMPLE_DISPLAY_PIPE_SHADOW_PLANE_FUNCS,
* };
*
* void driver_pipe_enable(struct drm_simple_display_pipe *pipe,
* struct drm_crtc_state *crtc_state,
* struct drm_plane_state *plane_state)
* {
* struct drm_shadow_plane_state *shadow_plane_state =
* to_drm_shadow_plane_state(plane_state);
*
* // access shadow buffer via shadow_plane_state->map
* }
*/
/*
* Plane Helpers
*/
/**
* drm_gem_plane_helper_prepare_fb() - Prepare a GEM backed framebuffer
* @plane: Plane
* @state: Plane state the fence will be attached to
*
* This function extracts the exclusive fence from &drm_gem_object.resv and
* attaches it to plane state for the atomic helper to wait on. This is
* necessary to correctly implement implicit synchronization for any buffers
* shared as a struct &dma_buf. This function can be used as the
* &drm_plane_helper_funcs.prepare_fb callback.
*
* There is no need for &drm_plane_helper_funcs.cleanup_fb hook for simple
* GEM based framebuffer drivers which have their buffers always pinned in
* memory.
*
* This function is the default implementation for GEM drivers of
* &drm_plane_helper_funcs.prepare_fb if no callback is provided.
*/
int drm_gem_plane_helper_prepare_fb(struct drm_plane *plane,
struct drm_plane_state *state)
{
struct dma_fence *fence = dma_fence_get(state->fence);
enum dma_resv_usage usage;
size_t i;
int ret;
if (!state->fb)
return 0;
/*
* Only add the kernel fences here if there is already a fence set via
* explicit fencing interfaces on the atomic ioctl.
*
* This way explicit fencing can be used to overrule implicit fencing,
* which is important to make explicit fencing use-cases work: One
* example is using one buffer for 2 screens with different refresh
* rates. Implicit fencing will clamp rendering to the refresh rate of
* the slower screen, whereas explicit fence allows 2 independent
* render and display loops on a single buffer. If a driver allows
* obeys both implicit and explicit fences for plane updates, then it
* will break all the benefits of explicit fencing.
*/
usage = fence ? DMA_RESV_USAGE_KERNEL : DMA_RESV_USAGE_WRITE;
for (i = 0; i < state->fb->format->num_planes; ++i) {
struct drm_gem_object *obj = drm_gem_fb_get_obj(state->fb, i);
struct dma_fence *new;
if (!obj) {
ret = -EINVAL;
goto error;
}
ret = dma_resv_get_singleton(obj->resv, usage, &new);
if (ret)
goto error;
if (new && fence) {
struct dma_fence_chain *chain = dma_fence_chain_alloc();
if (!chain) {
ret = -ENOMEM;
goto error;
}
dma_fence_chain_init(chain, fence, new, 1);
fence = &chain->base;
} else if (new) {
fence = new;
}
}
dma_fence_put(state->fence);
state->fence = fence;
return 0;
error:
dma_fence_put(fence);
return ret;
}
EXPORT_SYMBOL_GPL(drm_gem_plane_helper_prepare_fb);
/*
* Shadow-buffered Planes
*/
/**
* __drm_gem_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
* @plane: the plane
* @new_shadow_plane_state: the new shadow-buffered plane state
*
* This function duplicates shadow-buffered plane state. This is helpful for drivers
* that subclass struct drm_shadow_plane_state.
*
* The function does not duplicate existing mappings of the shadow buffers.
* Mappings are maintained during the atomic commit by the plane's prepare_fb
* and cleanup_fb helpers. See drm_gem_prepare_shadow_fb() and drm_gem_cleanup_shadow_fb()
* for corresponding helpers.
*/
void
__drm_gem_duplicate_shadow_plane_state(struct drm_plane *plane,
struct drm_shadow_plane_state *new_shadow_plane_state)
{
struct drm_plane_state *plane_state = plane->state;
struct drm_shadow_plane_state *shadow_plane_state =
to_drm_shadow_plane_state(plane_state);
__drm_atomic_helper_plane_duplicate_state(plane, &new_shadow_plane_state->base);
drm_format_conv_state_copy(&new_shadow_plane_state->fmtcnv_state,
&shadow_plane_state->fmtcnv_state);
}
EXPORT_SYMBOL(__drm_gem_duplicate_shadow_plane_state);
/**
* drm_gem_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
* @plane: the plane
*
* This function implements struct &drm_plane_funcs.atomic_duplicate_state for
* shadow-buffered planes. It assumes the existing state to be of type
* struct drm_shadow_plane_state and it allocates the new state to be of this
* type.
*
* The function does not duplicate existing mappings of the shadow buffers.
* Mappings are maintained during the atomic commit by the plane's prepare_fb
* and cleanup_fb helpers. See drm_gem_prepare_shadow_fb() and drm_gem_cleanup_shadow_fb()
* for corresponding helpers.
*
* Returns:
* A pointer to a new plane state on success, or NULL otherwise.
*/
struct drm_plane_state *
drm_gem_duplicate_shadow_plane_state(struct drm_plane *plane)
{
struct drm_plane_state *plane_state = plane->state;
struct drm_shadow_plane_state *new_shadow_plane_state;
if (!plane_state)
return NULL;
new_shadow_plane_state = kzalloc(sizeof(*new_shadow_plane_state), GFP_KERNEL);
if (!new_shadow_plane_state)
return NULL;
__drm_gem_duplicate_shadow_plane_state(plane, new_shadow_plane_state);
return &new_shadow_plane_state->base;
}
EXPORT_SYMBOL(drm_gem_duplicate_shadow_plane_state);
/**
* __drm_gem_destroy_shadow_plane_state - cleans up shadow-buffered plane state
* @shadow_plane_state: the shadow-buffered plane state
*
* This function cleans up shadow-buffered plane state. Helpful for drivers that
* subclass struct drm_shadow_plane_state.
*/
void __drm_gem_destroy_shadow_plane_state(struct drm_shadow_plane_state *shadow_plane_state)
{
drm_format_conv_state_release(&shadow_plane_state->fmtcnv_state);
__drm_atomic_helper_plane_destroy_state(&shadow_plane_state->base);
}
EXPORT_SYMBOL(__drm_gem_destroy_shadow_plane_state);
/**
* drm_gem_destroy_shadow_plane_state - deletes shadow-buffered plane state
* @plane: the plane
* @plane_state: the plane state of type struct drm_shadow_plane_state
*
* This function implements struct &drm_plane_funcs.atomic_destroy_state
* for shadow-buffered planes. It expects that mappings of shadow buffers
* have been released already.
*/
void drm_gem_destroy_shadow_plane_state(struct drm_plane *plane,
struct drm_plane_state *plane_state)
{
struct drm_shadow_plane_state *shadow_plane_state =
to_drm_shadow_plane_state(plane_state);
__drm_gem_destroy_shadow_plane_state(shadow_plane_state);
kfree(shadow_plane_state);
}
EXPORT_SYMBOL(drm_gem_destroy_shadow_plane_state);
/**
* __drm_gem_reset_shadow_plane - resets a shadow-buffered plane
* @plane: the plane
* @shadow_plane_state: the shadow-buffered plane state
*
* This function resets state for shadow-buffered planes. Helpful
* for drivers that subclass struct drm_shadow_plane_state.
*/
void __drm_gem_reset_shadow_plane(struct drm_plane *plane,
struct drm_shadow_plane_state *shadow_plane_state)
{
__drm_atomic_helper_plane_reset(plane, &shadow_plane_state->base);
drm_format_conv_state_init(&shadow_plane_state->fmtcnv_state);
}
EXPORT_SYMBOL(__drm_gem_reset_shadow_plane);
/**
* drm_gem_reset_shadow_plane - resets a shadow-buffered plane
* @plane: the plane
*
* This function implements struct &drm_plane_funcs.reset_plane for
* shadow-buffered planes. It assumes the current plane state to be
* of type struct drm_shadow_plane and it allocates the new state of
* this type.
*/
void drm_gem_reset_shadow_plane(struct drm_plane *plane)
{
struct drm_shadow_plane_state *shadow_plane_state;
if (plane->state) {
drm_gem_destroy_shadow_plane_state(plane, plane->state);
plane->state = NULL; /* must be set to NULL here */
}
shadow_plane_state = kzalloc(sizeof(*shadow_plane_state), GFP_KERNEL);
if (!shadow_plane_state)
return;
__drm_gem_reset_shadow_plane(plane, shadow_plane_state);
}
EXPORT_SYMBOL(drm_gem_reset_shadow_plane);
/**
* drm_gem_begin_shadow_fb_access - prepares shadow framebuffers for CPU access
* @plane: the plane
* @plane_state: the plane state of type struct drm_shadow_plane_state
*
* This function implements struct &drm_plane_helper_funcs.begin_fb_access. It
* maps all buffer objects of the plane's framebuffer into kernel address
* space and stores them in struct &drm_shadow_plane_state.map. The first data
* bytes are available in struct &drm_shadow_plane_state.data.
*
* See drm_gem_end_shadow_fb_access() for cleanup.
*
* Returns:
* 0 on success, or a negative errno code otherwise.
*/
int drm_gem_begin_shadow_fb_access(struct drm_plane *plane, struct drm_plane_state *plane_state)
{
struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
struct drm_framebuffer *fb = plane_state->fb;
if (!fb)
return 0;
return drm_gem_fb_vmap(fb, shadow_plane_state->map, shadow_plane_state->data);
}
EXPORT_SYMBOL(drm_gem_begin_shadow_fb_access);
/**
* drm_gem_end_shadow_fb_access - releases shadow framebuffers from CPU access
* @plane: the plane
* @plane_state: the plane state of type struct drm_shadow_plane_state
*
* This function implements struct &drm_plane_helper_funcs.end_fb_access. It
* undoes all effects of drm_gem_begin_shadow_fb_access() in reverse order.
*
* See drm_gem_begin_shadow_fb_access() for more information.
*/
void drm_gem_end_shadow_fb_access(struct drm_plane *plane, struct drm_plane_state *plane_state)
{
struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
struct drm_framebuffer *fb = plane_state->fb;
if (!fb)
return;
drm_gem_fb_vunmap(fb, shadow_plane_state->map);
}
EXPORT_SYMBOL(drm_gem_end_shadow_fb_access);
/**
* drm_gem_simple_kms_begin_shadow_fb_access - prepares shadow framebuffers for CPU access
* @pipe: the simple display pipe
* @plane_state: the plane state of type struct drm_shadow_plane_state
*
* This function implements struct drm_simple_display_funcs.begin_fb_access.
*
* See drm_gem_begin_shadow_fb_access() for details and
* drm_gem_simple_kms_cleanup_shadow_fb() for cleanup.
*
* Returns:
* 0 on success, or a negative errno code otherwise.
*/
int drm_gem_simple_kms_begin_shadow_fb_access(struct drm_simple_display_pipe *pipe,
struct drm_plane_state *plane_state)
{
return drm_gem_begin_shadow_fb_access(&pipe->plane, plane_state);
}
EXPORT_SYMBOL(drm_gem_simple_kms_begin_shadow_fb_access);
/**
* drm_gem_simple_kms_end_shadow_fb_access - releases shadow framebuffers from CPU access
* @pipe: the simple display pipe
* @plane_state: the plane state of type struct drm_shadow_plane_state
*
* This function implements struct drm_simple_display_funcs.end_fb_access.
* It undoes all effects of drm_gem_simple_kms_begin_shadow_fb_access() in
* reverse order.
*
* See drm_gem_simple_kms_begin_shadow_fb_access().
*/
void drm_gem_simple_kms_end_shadow_fb_access(struct drm_simple_display_pipe *pipe,
struct drm_plane_state *plane_state)
{
drm_gem_end_shadow_fb_access(&pipe->plane, plane_state);
}
EXPORT_SYMBOL(drm_gem_simple_kms_end_shadow_fb_access);
/**
* drm_gem_simple_kms_reset_shadow_plane - resets a shadow-buffered plane
* @pipe: the simple display pipe
*
* This function implements struct drm_simple_display_funcs.reset_plane
* for shadow-buffered planes.
*/
void drm_gem_simple_kms_reset_shadow_plane(struct drm_simple_display_pipe *pipe)
{
drm_gem_reset_shadow_plane(&pipe->plane);
}
EXPORT_SYMBOL(drm_gem_simple_kms_reset_shadow_plane);
/**
* drm_gem_simple_kms_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
* @pipe: the simple display pipe
*
* This function implements struct drm_simple_display_funcs.duplicate_plane_state
* for shadow-buffered planes. It does not duplicate existing mappings of the shadow
* buffers. Mappings are maintained during the atomic commit by the plane's prepare_fb
* and cleanup_fb helpers.
*
* Returns:
* A pointer to a new plane state on success, or NULL otherwise.
*/
struct drm_plane_state *
drm_gem_simple_kms_duplicate_shadow_plane_state(struct drm_simple_display_pipe *pipe)
{
return drm_gem_duplicate_shadow_plane_state(&pipe->plane);
}
EXPORT_SYMBOL(drm_gem_simple_kms_duplicate_shadow_plane_state);
/**
* drm_gem_simple_kms_destroy_shadow_plane_state - resets shadow-buffered plane state
* @pipe: the simple display pipe
* @plane_state: the plane state of type struct drm_shadow_plane_state
*
* This function implements struct drm_simple_display_funcs.destroy_plane_state
* for shadow-buffered planes. It expects that mappings of shadow buffers
* have been released already.
*/
void drm_gem_simple_kms_destroy_shadow_plane_state(struct drm_simple_display_pipe *pipe,
struct drm_plane_state *plane_state)
{
drm_gem_destroy_shadow_plane_state(&pipe->plane, plane_state);
}
EXPORT_SYMBOL(drm_gem_simple_kms_destroy_shadow_plane_state);
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