From ed20151a7699bb2c77eba3610199789a126940c4 Mon Sep 17 00:00:00 2001 From: Ville Syrjälä Date: Tue, 27 Nov 2018 20:20:04 +0200 Subject: drm/vblank: Allow dynamic per-crtc max_vblank_count MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On i965gm we need to adjust max_vblank_count dynamically depending on whether the TV encoder is used or not. To that end add a per-crtc max_vblank_count that takes precedence over its device wide counterpart. The driver can now call drm_crtc_set_max_vblank_count() to configure the per-crtc value before calling drm_vblank_on(). Also looks like there was some discussion about exynos needing similar treatment. v2: Drop the extra max_vblank_count!=0 check for the WARN(last!=current), will take care of it in i915 code (Daniel) WARN_ON(!inmodeset) (Daniel) WARN_ON(dev->max_vblank_count) Pimp up the docs (Daniel) Cc: stable@vger.kernel.org Cc: Inki Dae Cc: Daniel Vetter Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20181127182004.28885-1-ville.syrjala@linux.intel.com Reviewed-by: Daniel Vetter --- include/drm/drm_vblank.h | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'include/drm/drm_vblank.h') diff --git a/include/drm/drm_vblank.h b/include/drm/drm_vblank.h index 6ad9630d4f48..e528bb2f659d 100644 --- a/include/drm/drm_vblank.h +++ b/include/drm/drm_vblank.h @@ -128,6 +128,26 @@ struct drm_vblank_crtc { * @last: Protected by &drm_device.vbl_lock, used for wraparound handling. */ u32 last; + /** + * @max_vblank_count: + * + * Maximum value of the vblank registers for this crtc. This value +1 + * will result in a wrap-around of the vblank register. It is used + * by the vblank core to handle wrap-arounds. + * + * If set to zero the vblank core will try to guess the elapsed vblanks + * between times when the vblank interrupt is disabled through + * high-precision timestamps. That approach is suffering from small + * races and imprecision over longer time periods, hence exposing a + * hardware vblank counter is always recommended. + * + * This is the runtime configurable per-crtc maximum set through + * drm_crtc_set_max_vblank_count(). If this is used the driver + * must leave the device wide &drm_device.max_vblank_count at zero. + * + * If non-zero, &drm_crtc_funcs.get_vblank_counter must be set. + */ + u32 max_vblank_count; /** * @inmodeset: Tracks whether the vblank is disabled due to a modeset. * For legacy driver bit 2 additionally tracks whether an additional @@ -206,4 +226,6 @@ bool drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, void drm_calc_timestamping_constants(struct drm_crtc *crtc, const struct drm_display_mode *mode); wait_queue_head_t *drm_crtc_vblank_waitqueue(struct drm_crtc *crtc); +void drm_crtc_set_max_vblank_count(struct drm_crtc *crtc, + u32 max_vblank_count); #endif -- cgit v1.2.3