Hi all.
On Fri, Jul 26, 2019 at 11:06:58PM +0200, Sam Ravnborg wrote:
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.
Patch passes igt testing, and Michel was happy with it. It is now applied to drm-misc-next and pushed out.
With this we have one less user of drm_os_linux.h (only very few remains)
And one less cryptic macro use.
Sam
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@ravnborg.org Cc: "Michel Dänzer" michel@daenzer.net Cc: Sean Paul sean@poorly.run Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: Maxime Ripard maxime.ripard@bootlin.com Cc: David Airlie airlied@linux.ie Cc: Daniel Vetter daniel@ffwll.ch
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@lists.freedesktop.org, 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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