目录
[1. drm_mode_setcrtc](#1. drm_mode_setcrtc)
[1.1 根据应用传入的crtc_id找到crtc](#1.1 根据应用传入的crtc_id找到crtc)
[1.2 根据应用传入的fb_id,找到对应的drm_framebuffer](#1.2 根据应用传入的fb_id,找到对应的drm_framebuffer)
[1.3 根据应用传入的mode,创建一个drm_display_mode](#1.3 根据应用传入的mode,创建一个drm_display_mode)
[1.4 根据传入的set_connectors_ptr,找到驱动对应的connector](#1.4 根据传入的set_connectors_ptr,找到驱动对应的connector)
[1.5 将以上信息转为struct drm_mode_set并调用__drm_mode_set_config_internal](#1.5 将以上信息转为struct drm_mode_set并调用__drm_mode_set_config_internal)
[1.6 __drm_mode_set_config_internal](#1.6 __drm_mode_set_config_internal)
[2. drm_atomic_helper_set_config](#2. drm_atomic_helper_set_config)
[3. 流程图](#3. 流程图)
本文分析一下drm_mode_setcrtc。
1. drm_mode_setcrtc
1.1 根据应用传入的crtc_id找到crtc
cpp
int drm_mode_setcrtc(struct drm_device *dev, void *data,
struct drm_file *file_priv)
{
......
crtc = drm_crtc_find(dev, crtc_req->crtc_id);
if (!crtc) {
DRM_DEBUG_KMS("Unknown CRTC ID %d\n", crtc_req->crtc_id);
return -ENOENT;
}
DRM_DEBUG_KMS("[CRTC:%d:%s]\n", crtc->base.id, crtc->name);
1.2 根据应用传入的fb_id,找到对应的drm_framebuffer
cpp
if (crtc_req->mode_valid) {
/* If we have a mode we need a framebuffer. */
/* If we pass -1, set the mode with the currently bound fb */
if (crtc_req->fb_id == -1) {
if (!crtc->primary->fb) {
DRM_DEBUG_KMS("CRTC doesn't have current FB\n");
ret = -EINVAL;
goto out;
}
fb = crtc->primary->fb;
/* Make refcounting symmetric with the lookup path. */
drm_framebuffer_get(fb);
} else {
fb = drm_framebuffer_lookup(dev, crtc_req->fb_id);
if (!fb) {
DRM_DEBUG_KMS("Unknown FB ID%d\n",
crtc_req->fb_id);
ret = -ENOENT;
goto out;
}
1.3 根据应用传入的mode,创建一个drm_display_mode
cpp
mode = drm_mode_create(dev);
if (!mode) {
ret = -ENOMEM;
goto out;
}
ret = drm_mode_convert_umode(mode, &crtc_req->mode);
if (ret) {
DRM_DEBUG_KMS("Invalid mode\n");
goto out;
}
/*
* Check whether the primary plane supports the fb pixel format.
* Drivers not implementing the universal planes API use a
* default formats list provided by the DRM core which doesn't
* match real hardware capabilities. Skip the check in that
* case.
*/
if (!crtc->primary->format_default) {
ret = drm_plane_check_pixel_format(crtc->primary,
fb->format->format);
if (ret) {
struct drm_format_name_buf format_name;
DRM_DEBUG_KMS("Invalid pixel format %s\n",
drm_get_format_name(fb->format->format,
&format_name));
goto out;
}
}
ret = drm_crtc_check_viewport(crtc, crtc_req->x, crtc_req->y,
mode, fb);
if (ret)
goto out;
1.4 根据传入的set_connectors_ptr,找到驱动对应的connector
cpp
for (i = 0; i < crtc_req->count_connectors; i++) {
connector_set[i] = NULL;
set_connectors_ptr = (uint32_t __user *)(unsigned long)crtc_req->set_connectors_ptr;
if (get_user(out_id, &set_connectors_ptr[i])) {
ret = -EFAULT;
goto out;
}
connector = drm_connector_lookup(dev, out_id);
if (!connector) {
DRM_DEBUG_KMS("Connector id %d unknown\n",
out_id);
ret = -ENOENT;
goto out;
}
DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
connector->base.id,
connector->name);
connector_set[i] = connector;
}
1.5 将以上信息转为struct drm_mode_set并调用__drm_mode_set_config_internal
cpp
set.crtc = crtc;
set.x = crtc_req->x;
set.y = crtc_req->y;
set.mode = mode;
set.connectors = connector_set;
set.num_connectors = crtc_req->count_connectors;
set.fb = fb;
ret = __drm_mode_set_config_internal(&set, &ctx);
1.6 __drm_mode_set_config_internal
cpp
static int __drm_mode_set_config_internal(struct drm_mode_set *set,
struct drm_modeset_acquire_ctx *ctx)
{
struct drm_crtc *crtc = set->crtc;
struct drm_framebuffer *fb;
struct drm_crtc *tmp;
int ret;
/*
* NOTE: ->set_config can also disable other crtcs (if we steal all
* connectors from it), hence we need to refcount the fbs across all
* crtcs. Atomic modeset will have saner semantics ...
*/
drm_for_each_crtc(tmp, crtc->dev)
tmp->primary->old_fb = tmp->primary->fb;
fb = set->fb;
ret = crtc->funcs->set_config(set, ctx);
if (ret == 0) {
crtc->primary->crtc = crtc;
crtc->primary->fb = fb;
}
drm_for_each_crtc(tmp, crtc->dev) {
if (tmp->primary->fb)
drm_framebuffer_get(tmp->primary->fb);
if (tmp->primary->old_fb)
drm_framebuffer_put(tmp->primary->old_fb);
tmp->primary->old_fb = NULL;
}
return ret;
}
只要是调用ret = crtc->funcs->set_config(set, ctx),即drm_atomic_helper_set_config,
cpp
static const struct drm_crtc_funcs malidp_crtc_funcs = {
.gamma_set = drm_atomic_helper_legacy_gamma_set,
.destroy = drm_crtc_cleanup,
.set_config = drm_atomic_helper_set_config,
.page_flip = drm_atomic_helper_page_flip,
.reset = malidp_crtc_reset,
.atomic_duplicate_state = malidp_crtc_duplicate_state,
.atomic_destroy_state = malidp_crtc_destroy_state,
.enable_vblank = malidp_crtc_enable_vblank,
.disable_vblank = malidp_crtc_disable_vblank,
};
2. drm_atomic_helper_set_config
cpp
int drm_atomic_helper_set_config(struct drm_mode_set *set,
struct drm_modeset_acquire_ctx *ctx)
{
struct drm_atomic_state *state;
struct drm_crtc *crtc = set->crtc;
int ret = 0;
state = drm_atomic_state_alloc(crtc->dev);
if (!state)
return -ENOMEM;
state->acquire_ctx = ctx;
ret = __drm_atomic_helper_set_config(set, state);
if (ret != 0)
goto fail;
ret = handle_conflicting_encoders(state, true);
if (ret)
goto fail;
ret = drm_atomic_commit(state);
fail:
drm_atomic_state_put(state);
return ret;
}
drm_atomic_helper_set_config主要涉及到结构体struct drm_atomic_state和drm_atomic_commit函数,我们后面会单独讨论这2个。