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-rw-r--r--drivers/gpu/drm/drm_atomic_helper.c10
-rw-r--r--drivers/gpu/drm/drm_vblank.c28
2 files changed, 37 insertions, 1 deletions
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 4511c2e07bb9..d7b73cd89b79 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -583,6 +583,7 @@ mode_valid(struct drm_atomic_state *state)
* &drm_crtc_state.connectors_changed is set when a connector is added or
* removed from the CRTC. &drm_crtc_state.active_changed is set when
* &drm_crtc_state.active changes, which is used for DPMS.
+ * &drm_crtc_state.no_vblank is set from the result of drm_dev_has_vblank().
* See also: drm_atomic_crtc_needs_modeset()
*
* IMPORTANT:
@@ -649,6 +650,11 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
return -EINVAL;
}
+
+ if (drm_dev_has_vblank(dev))
+ new_crtc_state->no_vblank = false;
+ else
+ new_crtc_state->no_vblank = true;
}
ret = handle_conflicting_encoders(state, false);
@@ -2215,7 +2221,9 @@ EXPORT_SYMBOL(drm_atomic_helper_wait_for_dependencies);
* when a job is queued, and any change to the pipeline that does not touch the
* connector is leading to timeouts when calling
* drm_atomic_helper_wait_for_vblanks() or
- * drm_atomic_helper_wait_for_flip_done().
+ * drm_atomic_helper_wait_for_flip_done(). In addition to writeback
+ * connectors, this function can also fake VBLANK events for CRTCs without
+ * VBLANK interrupt.
*
* This is part of the atomic helper support for nonblocking commits, see
* drm_atomic_helper_setup_commit() for an overview.
diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 1659b13b178c..27a99c486f02 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -69,6 +69,12 @@
* &drm_driver.max_vblank_count. In that case the vblank core only disables the
* vblanks after a timer has expired, which can be configured through the
* ``vblankoffdelay`` module parameter.
+ *
+ * Drivers for hardware without support for vertical-blanking interrupts
+ * must not call drm_vblank_init(). For such drivers, atomic helpers will
+ * automatically generate fake vblank events as part of the display update.
+ * This functionality also can be controlled by the driver by enabling and
+ * disabling struct drm_crtc_state.no_vblank.
*/
/* Retry timestamp calculation up to 3 times to satisfy
@@ -502,6 +508,28 @@ err:
EXPORT_SYMBOL(drm_vblank_init);
/**
+ * drm_dev_has_vblank - test if vblanking has been initialized for
+ * a device
+ * @dev: the device
+ *
+ * Drivers may call this function to test if vblank support is
+ * initialized for a device. For most hardware this means that vblanking
+ * can also be enabled.
+ *
+ * Atomic helpers use this function to initialize
+ * &drm_crtc_state.no_vblank. See also drm_atomic_helper_check_modeset().
+ *
+ * Returns:
+ * True if vblanking has been initialized for the given device, false
+ * otherwise.
+ */
+bool drm_dev_has_vblank(const struct drm_device *dev)
+{
+ return dev->num_crtcs != 0;
+}
+EXPORT_SYMBOL(drm_dev_has_vblank);
+
+/**
* drm_crtc_vblank_waitqueue - get vblank waitqueue for the CRTC
* @crtc: which CRTC's vblank waitqueue to retrieve
*