From d0bb96b4be69feea97f16de5306c35e280658931 Mon Sep 17 00:00:00 2001 From: Dhinakaran Pandiyan Date: Fri, 2 Feb 2018 21:13:01 -0800 Subject: drm/vblank: Restoring vblank counts after device PM events. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The HW frame counter can get reset if device enters a low power state after vblank interrupts were disabled. This messes up any following vblank count update as a negative diff (huge unsigned diff) is calculated from the HW frame counter change. We cannot ignore negative diffs altogther as there could be legitimate wrap arounds. So, allow drivers to update vblank->count with missed vblanks for the time interrupts were disabled. This is similar to _crtc_vblank_on() except that vblanks interrupts are not enabled at the end as this function is expected to be called from the driver _enable_vblank() vfunc. v2: drm_crtc_vblank_restore should take crtc as arg. (Chris) Add docs and sprinkle some asserts. Cc: Daniel Vetter Cc: Chris Wilson Cc: Michel Dänzer Signed-off-by: Dhinakaran Pandiyan Reviewed-by: Rodrigo Vivi Acked-by: Daniel Vetter Signed-off-by: Rodrigo Vivi Link: https://patchwork.freedesktop.org/patch/msgid/20180203051302.9974-9-dhinakaran.pandiyan@intel.com --- include/drm/drm_vblank.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/drm/drm_vblank.h') diff --git a/include/drm/drm_vblank.h b/include/drm/drm_vblank.h index a4c3b0a0a197..16d46e2a6854 100644 --- a/include/drm/drm_vblank.h +++ b/include/drm/drm_vblank.h @@ -180,6 +180,8 @@ void drm_crtc_vblank_off(struct drm_crtc *crtc); void drm_crtc_vblank_reset(struct drm_crtc *crtc); void drm_crtc_vblank_on(struct drm_crtc *crtc); u64 drm_crtc_accurate_vblank_count(struct drm_crtc *crtc); +void drm_vblank_restore(struct drm_device *dev, unsigned int pipe); +void drm_crtc_vblank_restore(struct drm_crtc *crtc); bool drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, unsigned int pipe, int *max_error, -- cgit v1.2.3