drm/doc: vblank cleanup
Unify and review everything, plus make sure it's all correct markup.
Drop the kernel-doc for internal functions. Also rework the overview
section, it's become rather outdated.
Unfortuantely the kernel-doc in drm_driver isn't rendered yet, but
that will change as soon as drm_driver is kernel-docified properly.
Also document properly that drm_vblank_cleanup is optional, the core
calls this already.
v2: Make it clear that cleanup happens in drm_dev_fini for drivers
with their own ->release callback (Thierry).
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170524145212.27837-11-daniel.vetter@ffwll.ch
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 39df16a..3aa3809 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -387,22 +387,49 @@ struct drm_device {
bool irq_enabled;
int irq;
- /*
+ /**
+ * @vblank_disable_immediate:
+ *
* If true, vblank interrupt will be disabled immediately when the
* refcount drops to zero, as opposed to via the vblank disable
* timer.
- * This can be set to true it the hardware has a working vblank
- * counter and the driver uses drm_vblank_on() and drm_vblank_off()
- * appropriately.
+ *
+ * This can be set to true it the hardware has a working vblank counter
+ * with high-precision timestamping (otherwise there are races) and the
+ * driver uses drm_crtc_vblank_on() and drm_crtc_vblank_off()
+ * appropriately. See also @max_vblank_count and
+ * &drm_crtc_funcs.get_vblank_counter.
*/
bool vblank_disable_immediate;
- /* array of size num_crtcs */
+ /**
+ * @vblank:
+ *
+ * Array of vblank tracking structures, one per &struct drm_crtc. For
+ * historical reasons (vblank support predates kernel modesetting) this
+ * is free-standing and not part of &struct drm_crtc itself. It must be
+ * initialized explicitly by calling drm_vblank_init().
+ */
struct drm_vblank_crtc *vblank;
spinlock_t vblank_time_lock; /**< Protects vblank count and time updates during vblank enable/disable */
spinlock_t vbl_lock;
+ /**
+ * @max_vblank_count:
+ *
+ * Maximum value of the vblank registers. This value +1 will result in a
+ * wrap-around of the vblank register. It is used by the vblank core to
+ * handle wrap-arounds.
+ *
+ * If set to zero the vblank core will try to guess the elapsed vblanks
+ * between times when the vblank interrupt is disabled through
+ * high-precision timestamps. That approach is suffering from small
+ * races and imprecision over longer time periods, hence exposing a
+ * hardware vblank counter is always recommended.
+ *
+ * If non-zeor, &drm_crtc_funcs.get_vblank_counter must be set.
+ */
u32 max_vblank_count; /**< size of vblank counter register */
/**
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 629a5fe..3a911a6 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -685,6 +685,9 @@ struct drm_crtc_funcs {
* drm_crtc_vblank_off() and drm_crtc_vblank_on() when disabling or
* enabling a CRTC.
*
+ * See also &drm_device.vblank_disable_immediate and
+ * &drm_device.max_vblank_count.
+ *
* Returns:
*
* Raw vblank counter value.