[RFC 2/7] drm: Add GEM backed framebuffer library
Noralf Trønnes
noralf at tronnes.org
Wed Jul 12 13:46:00 UTC 2017
Add a library for drivers that can use a simple representation
of a GEM backed framebuffer.
Signed-off-by: Noralf Trønnes <noralf at tronnes.org>
---
drivers/gpu/drm/Makefile | 2 +-
drivers/gpu/drm/drm_fb_gem_helper.c | 248 ++++++++++++++++++++++++++++++++++++
include/drm/drm_fb_gem_helper.h | 64 ++++++++++
3 files changed, 313 insertions(+), 1 deletion(-)
create mode 100644 drivers/gpu/drm/drm_fb_gem_helper.c
create mode 100644 include/drm/drm_fb_gem_helper.h
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 24a066e..83d8b09 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -33,7 +33,7 @@ drm_kms_helper-y := drm_crtc_helper.o drm_dp_helper.o drm_probe_helper.o \
drm_plane_helper.o drm_dp_mst_topology.o drm_atomic_helper.o \
drm_kms_helper_common.o drm_dp_dual_mode_helper.o \
drm_simple_kms_helper.o drm_modeset_helper.o \
- drm_scdc_helper.o
+ drm_scdc_helper.o drm_fb_gem_helper.o
drm_kms_helper-$(CONFIG_DRM_PANEL_BRIDGE) += bridge/panel.o
drm_kms_helper-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
diff --git a/drivers/gpu/drm/drm_fb_gem_helper.c b/drivers/gpu/drm/drm_fb_gem_helper.c
new file mode 100644
index 0000000..9a0da09
--- /dev/null
+++ b/drivers/gpu/drm/drm_fb_gem_helper.c
@@ -0,0 +1,248 @@
+/*
+ * drm fb gem helper functions
+ *
+ * Copyright (C) 2017 Noralf Trønnes
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/dma-buf.h>
+#include <linux/dma-mapping.h>
+#include <linux/module.h>
+#include <linux/reservation.h>
+
+#include <drm/drmP.h>
+#include <drm/drm_atomic.h>
+#include <drm/drm_crtc.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_fb_helper.h>
+#include <drm/drm_fb_gem_helper.h>
+#include <drm/drm_gem.h>
+
+/**
+ * drm_fb_gem_get_obj() - Get GEM object for framebuffer
+ * @fb: The framebuffer
+ * @plane: Which plane
+ *
+ * Returns the GEM object for given framebuffer.
+ */
+struct drm_gem_object *drm_fb_gem_get_obj(struct drm_framebuffer *fb,
+ unsigned int plane)
+{
+ struct drm_fb_gem *fb_gem = to_fb_gem(fb);
+
+ if (plane >= 4)
+ return NULL;
+
+ return fb_gem->obj[plane];
+}
+EXPORT_SYMBOL_GPL(drm_fb_gem_get_obj);
+
+/**
+ * drm_fb_gem_alloc - Allocate GEM backed framebuffer
+ * @dev: DRM device
+ * @mode_cmd: metadata from the userspace fb creation request
+ * @obj: GEM object nacking the framebuffer
+ * @num_planes: Number of planes
+ * @funcs: vtable to be used for the new framebuffer object
+ *
+ * Returns:
+ * Allocated struct drm_fb_gem * or error encoded pointer.
+ */
+struct drm_fb_gem *
+drm_fb_gem_alloc(struct drm_device *dev,
+ const struct drm_mode_fb_cmd2 *mode_cmd,
+ struct drm_gem_object **obj, unsigned int num_planes,
+ const struct drm_framebuffer_funcs *funcs)
+{
+ struct drm_fb_gem *fb_gem;
+ int ret, i;
+
+ fb_gem = kzalloc(sizeof(*fb_gem), GFP_KERNEL);
+ if (!fb_gem)
+ return ERR_PTR(-ENOMEM);
+
+ drm_helper_mode_fill_fb_struct(dev, &fb_gem->base, mode_cmd);
+
+ for (i = 0; i < num_planes; i++)
+ fb_gem->obj[i] = obj[i];
+
+ ret = drm_framebuffer_init(dev, &fb_gem->base, funcs);
+ if (ret) {
+ dev_err(dev->dev, "Failed to initialize framebuffer: %d\n", ret);
+ kfree(fb_gem);
+ return ERR_PTR(ret);
+ }
+
+ return fb_gem;
+}
+EXPORT_SYMBOL(drm_fb_gem_alloc);
+
+/**
+ * drm_fb_gem_destroy - Free GEM backed framebuffer
+ * @fb: DRM framebuffer
+ *
+ * Frees a GEM backed framebuffer with it's backing buffer(s) and the structure
+ * itself. Drivers can use this as their &drm_framebuffer_funcs->destroy
+ * callback.
+ */
+void drm_fb_gem_destroy(struct drm_framebuffer *fb)
+{
+ struct drm_fb_gem *fb_gem = to_fb_gem(fb);
+ int i;
+
+ for (i = 0; i < 4; i++) {
+ if (fb_gem->obj[i])
+ drm_gem_object_put_unlocked(fb_gem->obj[i]);
+ }
+
+ drm_framebuffer_cleanup(fb);
+ kfree(fb_gem);
+}
+EXPORT_SYMBOL(drm_fb_gem_destroy);
+
+/**
+ * drm_fb_gem_create_handle - Create handle for GEM backed framebuffer
+ * @fb: DRM framebuffer
+ * @file: drm file
+ * @handle: handle created
+ *
+ * Drivers can use this as their &drm_framebuffer_funcs->create_handle
+ * callback.
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
+int drm_fb_gem_create_handle(struct drm_framebuffer *fb, struct drm_file *file,
+ unsigned int *handle)
+{
+ struct drm_fb_gem *fb_gem = to_fb_gem(fb);
+
+ return drm_gem_handle_create(file, fb_gem->obj[0], handle);
+}
+EXPORT_SYMBOL(drm_fb_gem_create_handle);
+
+/**
+ * drm_fb_gem_create_with_funcs() - helper function for the
+ * &drm_mode_config_funcs.fb_create
+ * callback
+ * @dev: DRM device
+ * @file: drm file for the ioctl call
+ * @mode_cmd: metadata from the userspace fb creation request
+ * @funcs: vtable to be used for the new framebuffer object
+ *
+ * This can be used to set &drm_framebuffer_funcs for drivers that need the
+ * &drm_framebuffer_funcs.dirty callback. Use drm_fb_gem_create() if you don't
+ * need to change &drm_framebuffer_funcs.
+ */
+struct drm_framebuffer *
+drm_fb_gem_create_with_funcs(struct drm_device *dev, struct drm_file *file,
+ const struct drm_mode_fb_cmd2 *mode_cmd,
+ const struct drm_framebuffer_funcs *funcs)
+{
+ const struct drm_format_info *info;
+ struct drm_gem_object *objs[4];
+ struct drm_fb_gem *fb_gem;
+ int ret, i;
+
+ info = drm_get_format_info(dev, mode_cmd);
+ if (!info)
+ return ERR_PTR(-EINVAL);
+
+ for (i = 0; i < info->num_planes; i++) {
+ unsigned int width = mode_cmd->width / (i ? info->hsub : 1);
+ unsigned int height = mode_cmd->height / (i ? info->vsub : 1);
+ unsigned int min_size;
+
+ objs[i] = drm_gem_object_lookup(file, mode_cmd->handles[i]);
+ if (!objs[i]) {
+ dev_err(dev->dev, "Failed to lookup GEM object\n");
+ ret = -ENOENT;
+ goto err_gem_object_put;
+ }
+
+ min_size = (height - 1) * mode_cmd->pitches[i]
+ + width * info->cpp[i]
+ + mode_cmd->offsets[i];
+
+ if (objs[i]->size < min_size) {
+ drm_gem_object_put_unlocked(objs[i]);
+ ret = -EINVAL;
+ goto err_gem_object_put;
+ }
+ }
+
+ fb_gem = drm_fb_gem_alloc(dev, mode_cmd, objs, i, funcs);
+ if (IS_ERR(fb_gem)) {
+ ret = PTR_ERR(fb_gem);
+ goto err_gem_object_put;
+ }
+
+ return &fb_gem->base;
+
+err_gem_object_put:
+ for (i--; i >= 0; i--)
+ drm_gem_object_put_unlocked(objs[i]);
+
+ return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(drm_fb_gem_create_with_funcs);
+
+static struct drm_framebuffer_funcs drm_fb_gem_fb_funcs = {
+ .destroy = drm_fb_gem_destroy,
+ .create_handle = drm_fb_gem_create_handle,
+};
+
+/**
+ * drm_fb_gem_create() - &drm_mode_config_funcs.fb_create callback function
+ * @dev: DRM device
+ * @file: drm file for the ioctl call
+ * @mode_cmd: metadata from the userspace fb creation request
+ *
+ * If your hardware has special alignment or pitch requirements these should be
+ * checked before calling this function. Use drm_fb_gem_create_with_funcs() if
+ * you need to set &drm_framebuffer_funcs.dirty.
+ */
+struct drm_framebuffer *
+drm_fb_gem_create(struct drm_device *dev, struct drm_file *file,
+ const struct drm_mode_fb_cmd2 *mode_cmd)
+{
+ return drm_fb_gem_create_with_funcs(dev, file, mode_cmd,
+ &drm_fb_gem_fb_funcs);
+}
+EXPORT_SYMBOL_GPL(drm_fb_gem_create);
+
+/**
+ * drm_fb_gem_prepare_fb() - Prepare gem framebuffer
+ * @plane: Which plane
+ * @state: Plane state attach fence to
+ *
+ * This should be set as the &struct drm_plane_helper_funcs.prepare_fb hook.
+ *
+ * This function checks if the plane FB has an dma-buf attached, extracts
+ * the exclusive fence and attaches it to plane state for the atomic helper
+ * to wait on.
+ *
+ * There is no need for cleanup_fb for gem based framebuffer drivers.
+ */
+int drm_fb_gem_prepare_fb(struct drm_plane *plane,
+ struct drm_plane_state *state)
+{
+ struct dma_buf *dma_buf;
+ struct dma_fence *fence;
+
+ if ((plane->state->fb == state->fb) || !state->fb)
+ return 0;
+
+ dma_buf = drm_fb_gem_get_obj(state->fb, 0)->dma_buf;
+ if (dma_buf) {
+ fence = reservation_object_get_excl_rcu(dma_buf->resv);
+ drm_atomic_set_fence_for_plane(state, fence);
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(drm_fb_gem_prepare_fb);
diff --git a/include/drm/drm_fb_gem_helper.h b/include/drm/drm_fb_gem_helper.h
new file mode 100644
index 0000000..405a1e1
--- /dev/null
+++ b/include/drm/drm_fb_gem_helper.h
@@ -0,0 +1,64 @@
+#ifndef __DRM_FB_GEM_HELPER_H__
+#define __DRM_FB_GEM_HELPER_H__
+
+#include <drm/drm_framebuffer.h>
+
+struct drm_gem_shmem_object;
+struct drm_mode_fb_cmd2;
+struct drm_plane;
+struct drm_plane_state;
+
+/**
+ * struct drm_fb_gem - GEM backed framebuffer
+ */
+struct drm_fb_gem {
+ /**
+ * @base: Base DRM framebuffer
+ */
+ struct drm_framebuffer base;
+ /**
+ * @obj: GEM object array backing the framebuffer. One object per
+ * plane.
+ */
+ struct drm_gem_object *obj[4];
+};
+
+static inline struct drm_fb_gem *to_fb_gem(struct drm_framebuffer *fb)
+{
+ return container_of(fb, struct drm_fb_gem, base);
+}
+
+struct drm_gem_object *drm_fb_gem_get_obj(struct drm_framebuffer *fb,
+ unsigned int plane);
+struct drm_fb_gem *
+drm_fb_gem_alloc(struct drm_device *dev,
+ const struct drm_mode_fb_cmd2 *mode_cmd,
+ struct drm_gem_object **obj, unsigned int num_planes,
+ const struct drm_framebuffer_funcs *funcs);
+void drm_fb_gem_destroy(struct drm_framebuffer *fb);
+int drm_fb_gem_create_handle(struct drm_framebuffer *fb, struct drm_file *file,
+ unsigned int *handle);
+
+struct drm_framebuffer *
+drm_fb_gem_create_with_funcs(struct drm_device *dev, struct drm_file *file,
+ const struct drm_mode_fb_cmd2 *mode_cmd,
+ const struct drm_framebuffer_funcs *funcs);
+struct drm_framebuffer *
+drm_fb_gem_create(struct drm_device *dev, struct drm_file *file,
+ const struct drm_mode_fb_cmd2 *mode_cmd);
+
+
+int drm_fb_gem_prepare_fb(struct drm_plane *plane,
+ struct drm_plane_state *state);
+
+
+
+
+#ifdef CONFIG_DEBUG_FS
+struct seq_file;
+
+int drm_fb_gem_debugfs_show(struct seq_file *m, void *arg);
+#endif
+
+#endif
+
--
2.7.4
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