Bochs' 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/tiny/bochs.c | 68 ++++++++++++++++++++++++++++++++++++
1 file changed, 68 insertions(+)
diff --git a/drivers/gpu/drm/tiny/bochs.c b/drivers/gpu/drm/tiny/bochs.c
index 8706763af8fb..dbc6a15c1a58 100644
--- a/drivers/gpu/drm/tiny/bochs.c
+++ b/drivers/gpu/drm/tiny/bochs.c
@@ -21,6 +21,8 @@
#include <drm/drm_module.h>
#include <drm/drm_plane_helper.h>
#include <drm/drm_probe_helper.h>
+#include <drm/drm_vblank.h>
+#include <drm/drm_vblank_timer.h>
#include <video/vga.h>
@@ -95,6 +97,7 @@ struct bochs_device {
/* drm */
struct drm_plane primary_plane;
+ struct drm_vblank_timer vtimer;
struct drm_crtc crtc;
struct drm_encoder encoder;
struct drm_connector connector;
@@ -501,12 +504,35 @@ static int bochs_crtc_helper_atomic_check(struct drm_crtc
*crtc,
return drm_atomic_helper_check_crtc_primary_plane(crtc_state);
}
+static void bochs_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 bochs_crtc_helper_atomic_enable(struct drm_crtc *crtc,
struct drm_atomic_state *state)
{
struct bochs_device *bochs = to_bochs_device(crtc->dev);
bochs_hw_blank(bochs, false);
+ drm_crtc_vblank_on(crtc);
}
static void bochs_crtc_helper_atomic_disable(struct drm_crtc *crtc,
@@ -514,16 +540,44 @@ static void bochs_crtc_helper_atomic_disable(struct
drm_crtc *crtc,
{
struct bochs_device *bochs = to_bochs_device(crtc->dev);
+ drm_crtc_vblank_off(crtc);
bochs_hw_blank(bochs, true);
}
static const struct drm_crtc_helper_funcs bochs_crtc_helper_funcs = {
.mode_set_nofb = bochs_crtc_helper_mode_set_nofb,
.atomic_check = bochs_crtc_helper_atomic_check,
+ .atomic_flush = bochs_crtc_helper_atomic_flush,
.atomic_enable = bochs_crtc_helper_atomic_enable,
.atomic_disable = bochs_crtc_helper_atomic_disable,
};
+static int bochs_crtc_enable_vblank(struct drm_crtc *crtc)
+{
+ struct bochs_device *bochs = to_bochs_device(crtc->dev);
+
+ drm_vblank_timer_start(&bochs->vtimer);
+
+ return 0;
+}
+
+static void bochs_crtc_disable_vblank(struct drm_crtc *crtc)
+{
+ struct bochs_device *bochs = to_bochs_device(crtc->dev);
+
+ drm_vblank_timer_cancel(&bochs->vtimer);
+}
+
+static bool bochs_crtc_get_vblank_timestamp(struct drm_crtc *crtc,
+ int *max_error, ktime_t
*vblank_time,
+ bool in_vblank_irq)
+{
+ struct bochs_device *bochs = to_bochs_device(crtc->dev);
+
+ return drm_vblank_timer_get_vblank_timestamp(&bochs->vtimer, max_error,
+ vblank_time,
in_vblank_irq);
+}
+
static const struct drm_crtc_funcs bochs_crtc_funcs = {
.reset = drm_atomic_helper_crtc_reset,
.destroy = drm_crtc_cleanup,
@@ -531,6 +585,9 @@ static const struct drm_crtc_funcs bochs_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 = bochs_crtc_enable_vblank,
+ .disable_vblank = bochs_crtc_disable_vblank,
+ .get_vblank_timestamp = bochs_crtc_get_vblank_timestamp,
};
static const struct drm_encoder_funcs bochs_encoder_funcs = {
@@ -602,6 +659,7 @@ static int bochs_kms_init(struct bochs_device *bochs)
struct drm_crtc *crtc;
struct drm_connector *connector;
struct drm_encoder *encoder;
+ struct drm_vblank_timer *vtimer;
int ret;
ret = drmm_mode_config_init(dev);
@@ -651,6 +709,16 @@ static int bochs_kms_init(struct bochs_device *bochs)
drm_connector_attach_edid_property(connector);
drm_connector_attach_encoder(connector, encoder);
+ /* Vertical blanking */
+
+ ret = drm_vblank_init(dev, 1);
+ if (ret)
+ return ret;
+ vtimer = &bochs->vtimer;
+ ret = drmm_vblank_timer_init(vtimer, crtc, NULL);
+ if (ret)
+ return ret;
+
drm_mode_config_reset(dev);
return 0;
--
2.49.0
