DRM_WAIT_ON() is from the deprecated drm_os_linux header and
the modern replacement is the wait_event_*.
The return values differ, so a conversion is needed to
keep the original interface towards userspace.
Introduced a switch/case to make code obvious.
Analysis from Michel Dänzer:
The waiting condition rely on all relevant places where vblank_count
is modified calls wake_up(&vblank->queue).
drm_handle_vblank():
- Calls wake_up(&vblank->queue)
drm_vblank_enable():
- There is no need here because there can be no sleeping waiters
in the queue, because vblank->enabled == false immediately
terminates any waits.
drm_crtc_accurate_vblank_count():
- This is called from interrupt handlers, at least from
amdgpu_dm.c:dm_pflip_high_irq(). Not sure it needs to wake up
the queue though, the driver should call
drm_(crtc_)_handle_vblank anyway.
drm_vblank_disable_and_save():
- It can be called from an interrupt, via drm_handle_vblank ->
vblank_disable_fn. However, the only place where
drm_vblank_disable_and_save can be called with sleeping waiters
in the queue is in drm_crtc_vblank_off, which wakes up the queue
afterwards (which terminates all waits, because
vblank->enabled == false at this point).
v3:
- Added analysis to changelog from Michel Dänzer
- Moved return result handling inside if (req_seq != seq) (Daniel V)
- Reused more of the former logic - resulting in simpler code
- Dropped Reviewed-by from Sean Paul as this is a new implmentation
v2:
- Fix so the case where req_seq equals seq was handled properly
- quick hack to check if IGT became happy
- Only sent to igt, not to dri-devel
Signed-off-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
Cc: "Michel Dänzer" <michel@xxxxxxxxxxx>
Cc: Sean Paul <sean@xxxxxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Maxime Ripard <maxime.ripard@xxxxxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
---
This patch survives my testing here.
vbltest spits out the same value as before, and I can see something on
the screen.
Added intel-gfx@xxxxxxxxxxxxxxxxxxxxx, as IGT have identified troubles
with this in v1.
Sam
drivers/gpu/drm/drm_vblank.c | 25 ++++++++++++++++++++-----
1 file changed, 20 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 603ab105125d..fd1fbc77871f 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -31,7 +31,6 @@
#include <drm/drm_drv.h>
#include <drm/drm_framebuffer.h>
#include <drm/drm_print.h>
-#include <drm/drm_os_linux.h>
#include <drm/drm_vblank.h>
#include "drm_internal.h"
@@ -1670,12 +1669,28 @@ int drm_wait_vblank_ioctl(struct drm_device *dev, void *data,
}
if (req_seq != seq) {
+ int wait;
+
DRM_DEBUG("waiting on vblank count %llu, crtc %u\n",
req_seq, pipe);
- DRM_WAIT_ON(ret, vblank->queue, 3 * HZ,
- vblank_passed(drm_vblank_count(dev, pipe),
- req_seq) ||
- !READ_ONCE(vblank->enabled));
+ wait = wait_event_interruptible_timeout(vblank->queue,
+ vblank_passed(drm_vblank_count(dev, pipe), req_seq) ||
+ !READ_ONCE(vblank->enabled),
+ msecs_to_jiffies(3000));
+
+ switch (wait) {
+ case 0:
+ /* timeout */
+ ret = -EBUSY;
+ break;
+ case -ERESTARTSYS:
+ /* interrupted by signal */
+ ret = -EINTR;
+ break;
+ default:
+ ret = 0;
+ break;
+ }
}
if (ret != -EINTR) {
--
2.20.1
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