Before updating the display from the console's shadow buffer, the dirty
worker now waits for a vblank. This allows several screen updates to pile
up and acts as a rate limiter. If a DRM master is present, it could
interfere with the vblank. Don't wait in this case.
v3:
* add back helper->lock
* acquire DRM master status while waiting for vblank
v2:
* don't hold helper->lock while waiting for vblank
Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
---
drivers/gpu/drm/drm_fb_helper.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index fb9bff0f4581..ba20ad92fb90 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -404,8 +404,29 @@ static void drm_fb_helper_dirty_work(struct work_struct *work)
dirty_work);
struct drm_clip_rect *clip = &helper->dirty_clip;
struct drm_clip_rect clip_copy;
+ struct drm_crtc *crtc;
unsigned long flags;
void *vaddr;
+ int ret;
+
+ /*
+ * Rate-limit update frequency to vblank. If there's a DRM master
+ * present, it could interfere while we're waiting for the vblank
+ * event. Don't wait in this case.
+ */
+ mutex_lock(&helper->lock);
+ if (!drm_master_internal_acquire(helper->dev)) {
+ goto unlock;
+ }
+ crtc = helper->client.modesets[0].crtc;
+ ret = drm_crtc_vblank_get(crtc);
+ if (!ret) {
+ drm_crtc_wait_one_vblank(crtc);
+ drm_crtc_vblank_put(crtc);
+ }
+ drm_master_internal_release(helper->dev);
+unlock:
+ mutex_unlock(&helper->lock);
spin_lock_irqsave(&helper->dirty_lock, flags);
clip_copy = *clip;
--
2.23.0
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