i915/display/intel_vblank.c

27  *           start of vblank:
30  *           generate start of vblank interrupt (gen4+)
33  *           |          generate frame start interrupt (aka. vblank interrupt) (gmch)
62  *   (depending on TRANSCONF settings) after the start of vblank
73 	struct drm_vblank_crtc *vblank = drm_crtc_vblank_crtc(crtc);
74 	const struct drm_display_mode *mode = &vblank->hwmode;
83 	 * vblank wait before enabling the TV encoder and so we
84 	 * have to enable vblank interrupts while the frame counter
85 	 * is still in a working state. However the core vblank code
90 	if (!vblank->max_vblank_count)
100 	/* Start of vblank event occurs at start of hsync */
116 	 * Cook up a vblank counter by also checking the pixel
117 	 * counter against vblank start.
125 	struct drm_vblank_crtc *vblank = drm_crtc_vblank_crtc(crtc);
128 	if (!vblank->max_vblank_count)
137 	struct drm_vblank_crtc *vblank = drm_crtc_vblank_crtc(&crtc->base);
138 	const struct drm_display_mode *mode = &vblank->hwmode;
145 	 * next vblank just between the PIPE_FRMTMSTMP and TIMESTAMP_CTR
182 	struct drm_vblank_crtc *vblank = drm_crtc_vblank_crtc(&crtc->base);
183 	const struct drm_display_mode *mode = &vblank->hwmode;
205 	 * start of vblank, which also occurs at start of hsync (on the
217 	 * approx. 1/3 of a scanline before start of vblank. Unfortunately
218 	 * that means we can't tell whether we're in vblank or not while
220 	 * to 1 so that the vblank timestamps come out correct when we query
221 	 * the scanline counter from within the vblank interrupt handler.
222 	 * However if queried just before the start of vblank we'll get an
243 	struct drm_vblank_crtc *vblank = drm_crtc_vblank_crtc(&crtc->base);
244 	const struct drm_display_mode *mode = &vblank->hwmode;
260 	 * read it just before the start of vblank.  So try it again
261 	 * so we don't accidentally end up spanning a vblank frame
265 	 * bit and return the vblank start value; nor can we use the scanline
355 	 * Enter vblank critical section, as we will do multiple
374 		 * Already exiting vblank? If so, shift our position
376 		 * vblank end. This should make the generated timestamp
411 		 * Start of vblank interrupt is triggered at start of hsync,
412 		 * just prior to the first active line of vblank. However we
415 		 * the horizontal active of the first line in vblank, we would
432 	 * While in vblank, position will be negative
434 	 * vblank, position will be positive counting
690 	 * undelayed vblank, so with seamless M/N and LRR we must evade
693 	 * DSB execution waits for the transcoder's undelayed vblank,
701 /* must be called with vblank interrupt already enabled! */
744 	 * increment approx. 1/3 of a scanline before start of vblank.
745 	 * The registers still get latched at start of vblank however.
747 	 * line of vblank (since not the whole line is actually in
748 	 * vblank). And unfortunately we can't use the interrupt to