HyperV's virtual hardware does not provide vblank interrupts. Use a
vblank timer to simulate the interrupt in software. Rate-limits the
display's update frequency to the display-mode settings. Avoids
excessive CPU overhead with compositors that do not rate-limit their
output.
Signed-off-by: Thomas Zimmermann <tzimmerm...@suse.de>
---
drivers/gpu/drm/hyperv/hyperv_drm.h | 4 ++
drivers/gpu/drm/hyperv/hyperv_drm_modeset.c | 70 +++++++++++++++++++++
2 files changed, 74 insertions(+)
diff --git a/drivers/gpu/drm/hyperv/hyperv_drm.h
b/drivers/gpu/drm/hyperv/hyperv_drm.h
index 9e776112c03e..730e4a37545d 100644
--- a/drivers/gpu/drm/hyperv/hyperv_drm.h
+++ b/drivers/gpu/drm/hyperv/hyperv_drm.h
@@ -6,12 +6,16 @@
#ifndef _HYPERV_DRM_H_
#define _HYPERV_DRM_H_
+#include <drm/drm_vblank.h>
+#include <drm/drm_vblank_timer.h>
+
#define VMBUS_MAX_PACKET_SIZE 0x4000
struct hyperv_drm_device {
/* drm */
struct drm_device dev;
struct drm_plane plane;
+ struct drm_vblank_timer vtimer;
struct drm_crtc crtc;
struct drm_encoder encoder;
struct drm_connector connector;
diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
b/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
index f7d2e973f79e..ed19e471b96f 100644
--- a/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
+++ b/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
@@ -97,6 +97,28 @@ static const uint64_t hyperv_modifiers[] = {
DRM_FORMAT_MOD_INVALID
};
+static void hyperv_crtc_helper_atomic_flush(struct drm_crtc *crtc,
+ struct drm_atomic_state *state)
+{
+ struct drm_device *dev = crtc->dev;
+ struct drm_crtc_state *crtc_state =
drm_atomic_get_new_crtc_state(state, crtc);
+ struct drm_pending_vblank_event *event;
+
+ spin_lock_irq(&dev->event_lock);
+
+ event = crtc_state->event;
+ crtc_state->event = NULL;
+
+ if (event) {
+ if (drm_crtc_vblank_get(crtc) == 0)
+ drm_crtc_arm_vblank_event(crtc, event);
+ else
+ drm_crtc_send_vblank_event(crtc, event);
+ }
+
+ spin_unlock_irq(&dev->event_lock);
+}
+
static void hyperv_crtc_helper_atomic_enable(struct drm_crtc *crtc,
struct drm_atomic_state *state)
{
@@ -110,13 +132,49 @@ static void hyperv_crtc_helper_atomic_enable(struct
drm_crtc *crtc,
crtc_state->mode.hdisplay,
crtc_state->mode.vdisplay,
plane_state->fb->pitches[0]);
+
+ drm_crtc_vblank_on(crtc);
+}
+
+static void hyperv_crtc_helper_atomic_disable(struct drm_crtc *crtc,
+ struct drm_atomic_state
*crtc_state)
+{
+ drm_crtc_vblank_off(crtc);
}
static const struct drm_crtc_helper_funcs hyperv_crtc_helper_funcs = {
.atomic_check = drm_crtc_helper_atomic_check,
+ .atomic_flush = hyperv_crtc_helper_atomic_flush,
.atomic_enable = hyperv_crtc_helper_atomic_enable,
+ .atomic_disable = hyperv_crtc_helper_atomic_disable,
};
+static int hyperv_crtc_enable_vblank(struct drm_crtc *crtc)
+{
+ struct hyperv_drm_device *hv = to_hv(crtc->dev);
+
+ drm_vblank_timer_start(&hv->vtimer);
+
+ return 0;
+}
+
+static void hyperv_crtc_disable_vblank(struct drm_crtc *crtc)
+{
+ struct hyperv_drm_device *hv = to_hv(crtc->dev);
+
+ drm_vblank_timer_cancel(&hv->vtimer);
+}
+
+static bool hyperv_crtc_get_vblank_timestamp(struct drm_crtc *crtc,
+ int *max_error, ktime_t
*vblank_time,
+ bool in_vblank_irq)
+{
+ struct hyperv_drm_device *hv = to_hv(crtc->dev);
+
+ return drm_vblank_timer_get_vblank_timestamp(&hv->vtimer, max_error,
+ vblank_time,
in_vblank_irq);
+}
+
static const struct drm_crtc_funcs hyperv_crtc_funcs = {
.reset = drm_atomic_helper_crtc_reset,
.destroy = drm_crtc_cleanup,
@@ -124,6 +182,9 @@ static const struct drm_crtc_funcs hyperv_crtc_funcs = {
.page_flip = drm_atomic_helper_page_flip,
.atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
.atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
+ .enable_vblank = hyperv_crtc_enable_vblank,
+ .disable_vblank = hyperv_crtc_disable_vblank,
+ .get_vblank_timestamp = hyperv_crtc_get_vblank_timestamp,
};
static int hyperv_plane_atomic_check(struct drm_plane *plane,
@@ -285,6 +346,15 @@ int hyperv_mode_config_init(struct hyperv_drm_device *hv)
return ret;
}
+ /* Vertical blanking */
+
+ ret = drm_vblank_init(dev, 1);
+ if (ret)
+ return ret;
+ ret = drmm_vblank_timer_init(&hv->vtimer, &hv->crtc, NULL);
+ if (ret)
+ return ret;
+
drm_mode_config_reset(dev);
return 0;
--
2.49.0
