diff options
| author | Ville Syrjälä <ville.syrjala@linux.intel.com> | 2018-11-27 20:20:04 +0200 |
|---|---|---|
| committer | Marcel Ziswiler <marcel.ziswiler@toradex.com> | 2020-02-12 11:05:59 +0100 |
| commit | d3eadfc74a77454e3aa14c0116e423dbf6fe2f59 (patch) | |
| tree | ceae0d49a820239eacda8c434a36683d8494406c /include | |
| parent | 0c26ede12ef7b5d1cb4e8f76b9819df2643fa8cd (diff) | |
drm/vblank: Allow dynamic per-crtc max_vblank_count
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 <inki.dae@samsung.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181127182004.28885-1-ville.syrjala@linux.intel.com
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Diffstat (limited to 'include')
| -rw-r--r-- | include/drm/drm_device.h | 8 | ||||
| -rw-r--r-- | include/drm/drm_vblank.h | 22 |
2 files changed, 29 insertions, 1 deletions
diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h index 7c4fa32f3fc6..16cd3ba3d8d8 100644 --- a/include/drm/drm_device.h +++ b/include/drm/drm_device.h @@ -147,7 +147,13 @@ struct drm_device { * races and imprecision over longer time periods, hence exposing a * hardware vblank counter is always recommended. * - * If non-zeor, &drm_crtc_funcs.get_vblank_counter must be set. + * This is the statically configured device wide maximum. The driver + * can instead choose to use a runtime configurable per-crtc value + * &drm_vblank_crtc.max_vblank_count, in which case @max_vblank_count + * must be left at zero. See drm_crtc_set_max_vblank_count() on how + * to use the per-crtc value. + * + * If non-zero, &drm_crtc_funcs.get_vblank_counter must be set. */ u32 max_vblank_count; /**< size of vblank counter register */ diff --git a/include/drm/drm_vblank.h b/include/drm/drm_vblank.h index 7fba9efe4951..ec1ce941dec3 100644 --- a/include/drm/drm_vblank.h +++ b/include/drm/drm_vblank.h @@ -105,6 +105,26 @@ struct drm_vblank_crtc { */ 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 * temporary vblank reference has been acquired to paper over the @@ -177,4 +197,6 @@ 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 |