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![Daniel Vetter](/assets/img/avatar_default.png)
I got real badly confused when trying to review a fix from Ville for this. Let's try to document better what's required for this, and check the minimal settings at runtime - we can't check ofc that there's indeed no races in the driver callback. Also noticed that the drm_vblank_restore version is unused, so lets unexport that while at it. Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Ville Syrjala <ville.syrjala@linux.intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20210209101523.2954281-1-daniel.vetter@ffwll.ch
280 lines
9 KiB
C
280 lines
9 KiB
C
/*
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* Copyright 2016 Intel Corp.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
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* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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#ifndef _DRM_VBLANK_H_
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#define _DRM_VBLANK_H_
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#include <linux/seqlock.h>
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#include <linux/idr.h>
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#include <linux/poll.h>
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#include <linux/kthread.h>
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#include <drm/drm_file.h>
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#include <drm/drm_modes.h>
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struct drm_device;
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struct drm_crtc;
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struct drm_vblank_work;
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/**
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* struct drm_pending_vblank_event - pending vblank event tracking
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*/
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struct drm_pending_vblank_event {
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/**
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* @base: Base structure for tracking pending DRM events.
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*/
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struct drm_pending_event base;
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/**
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* @pipe: drm_crtc_index() of the &drm_crtc this event is for.
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*/
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unsigned int pipe;
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/**
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* @sequence: frame event should be triggered at
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*/
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u64 sequence;
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/**
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* @event: Actual event which will be sent to userspace.
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*/
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union {
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/**
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* @event.base: DRM event base class.
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*/
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struct drm_event base;
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/**
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* @event.vbl:
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*
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* Event payload for vblank events, requested through
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* either the MODE_PAGE_FLIP or MODE_ATOMIC IOCTL. Also
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* generated by the legacy WAIT_VBLANK IOCTL, but new userspace
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* should use MODE_QUEUE_SEQUENCE and &event.seq instead.
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*/
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struct drm_event_vblank vbl;
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/**
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* @event.seq: Event payload for the MODE_QUEUEU_SEQUENCE IOCTL.
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*/
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struct drm_event_crtc_sequence seq;
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} event;
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};
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/**
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* struct drm_vblank_crtc - vblank tracking for a CRTC
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*
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* This structure tracks the vblank state for one CRTC.
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*
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* Note that for historical reasons - the vblank handling code is still shared
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* with legacy/non-kms drivers - this is a free-standing structure not directly
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* connected to &struct drm_crtc. But all public interface functions are taking
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* a &struct drm_crtc to hide this implementation detail.
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*/
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struct drm_vblank_crtc {
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/**
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* @dev: Pointer to the &drm_device.
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*/
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struct drm_device *dev;
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/**
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* @queue: Wait queue for vblank waiters.
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*/
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wait_queue_head_t queue;
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/**
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* @disable_timer: Disable timer for the delayed vblank disabling
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* hysteresis logic. Vblank disabling is controlled through the
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* drm_vblank_offdelay module option and the setting of the
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* &drm_device.max_vblank_count value.
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*/
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struct timer_list disable_timer;
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/**
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* @seqlock: Protect vblank count and time.
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*/
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seqlock_t seqlock;
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/**
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* @count:
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*
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* Current software vblank counter.
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*
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* Note that for a given vblank counter value drm_crtc_handle_vblank()
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* and drm_crtc_vblank_count() or drm_crtc_vblank_count_and_time()
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* provide a barrier: Any writes done before calling
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* drm_crtc_handle_vblank() will be visible to callers of the later
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* functions, iff the vblank count is the same or a later one.
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*
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* IMPORTANT: This guarantee requires barriers, therefor never access
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* this field directly. Use drm_crtc_vblank_count() instead.
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*/
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atomic64_t count;
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/**
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* @time: Vblank timestamp corresponding to @count.
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*/
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ktime_t time;
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/**
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* @refcount: Number of users/waiters of the vblank interrupt. Only when
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* this refcount reaches 0 can the hardware interrupt be disabled using
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* @disable_timer.
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*/
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atomic_t refcount;
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/**
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* @last: Protected by &drm_device.vbl_lock, used for wraparound handling.
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*/
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u32 last;
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/**
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* @max_vblank_count:
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*
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* Maximum value of the vblank registers for this crtc. This value +1
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* will result in a wrap-around of the vblank register. It is used
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* by the vblank core to handle wrap-arounds.
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*
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* If set to zero the vblank core will try to guess the elapsed vblanks
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* between times when the vblank interrupt is disabled through
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* high-precision timestamps. That approach is suffering from small
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* races and imprecision over longer time periods, hence exposing a
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* hardware vblank counter is always recommended.
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*
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* This is the runtime configurable per-crtc maximum set through
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* drm_crtc_set_max_vblank_count(). If this is used the driver
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* must leave the device wide &drm_device.max_vblank_count at zero.
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*
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* If non-zero, &drm_crtc_funcs.get_vblank_counter must be set.
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*/
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u32 max_vblank_count;
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/**
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* @inmodeset: Tracks whether the vblank is disabled due to a modeset.
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* For legacy driver bit 2 additionally tracks whether an additional
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* temporary vblank reference has been acquired to paper over the
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* hardware counter resetting/jumping. KMS drivers should instead just
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* call drm_crtc_vblank_off() and drm_crtc_vblank_on(), which explicitly
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* save and restore the vblank count.
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*/
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unsigned int inmodeset;
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/**
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* @pipe: drm_crtc_index() of the &drm_crtc corresponding to this
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* structure.
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*/
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unsigned int pipe;
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/**
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* @framedur_ns: Frame/Field duration in ns, used by
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* drm_crtc_vblank_helper_get_vblank_timestamp() and computed by
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* drm_calc_timestamping_constants().
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*/
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int framedur_ns;
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/**
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* @linedur_ns: Line duration in ns, used by
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* drm_crtc_vblank_helper_get_vblank_timestamp() and computed by
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* drm_calc_timestamping_constants().
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*/
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int linedur_ns;
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/**
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* @hwmode:
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*
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* Cache of the current hardware display mode. Only valid when @enabled
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* is set. This is used by helpers like
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* drm_crtc_vblank_helper_get_vblank_timestamp(). We can't just access
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* the hardware mode by e.g. looking at &drm_crtc_state.adjusted_mode,
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* because that one is really hard to get from interrupt context.
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*/
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struct drm_display_mode hwmode;
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/**
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* @enabled: Tracks the enabling state of the corresponding &drm_crtc to
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* avoid double-disabling and hence corrupting saved state. Needed by
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* drivers not using atomic KMS, since those might go through their CRTC
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* disabling functions multiple times.
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*/
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bool enabled;
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/**
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* @worker: The &kthread_worker used for executing vblank works.
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*/
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struct kthread_worker *worker;
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/**
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* @pending_work: A list of scheduled &drm_vblank_work items that are
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* waiting for a future vblank.
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*/
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struct list_head pending_work;
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/**
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* @work_wait_queue: The wait queue used for signaling that a
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* &drm_vblank_work item has either finished executing, or was
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* cancelled.
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*/
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wait_queue_head_t work_wait_queue;
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};
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int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs);
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bool drm_dev_has_vblank(const struct drm_device *dev);
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u64 drm_crtc_vblank_count(struct drm_crtc *crtc);
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u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc,
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ktime_t *vblanktime);
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void drm_crtc_send_vblank_event(struct drm_crtc *crtc,
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struct drm_pending_vblank_event *e);
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void drm_crtc_arm_vblank_event(struct drm_crtc *crtc,
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struct drm_pending_vblank_event *e);
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void drm_vblank_set_event(struct drm_pending_vblank_event *e,
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u64 *seq,
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ktime_t *now);
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bool drm_handle_vblank(struct drm_device *dev, unsigned int pipe);
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bool drm_crtc_handle_vblank(struct drm_crtc *crtc);
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int drm_crtc_vblank_get(struct drm_crtc *crtc);
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void drm_crtc_vblank_put(struct drm_crtc *crtc);
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void drm_wait_one_vblank(struct drm_device *dev, unsigned int pipe);
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void drm_crtc_wait_one_vblank(struct drm_crtc *crtc);
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void drm_crtc_vblank_off(struct drm_crtc *crtc);
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void drm_crtc_vblank_reset(struct drm_crtc *crtc);
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void drm_crtc_vblank_on(struct drm_crtc *crtc);
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u64 drm_crtc_accurate_vblank_count(struct drm_crtc *crtc);
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void drm_crtc_vblank_restore(struct drm_crtc *crtc);
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void drm_calc_timestamping_constants(struct drm_crtc *crtc,
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const struct drm_display_mode *mode);
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wait_queue_head_t *drm_crtc_vblank_waitqueue(struct drm_crtc *crtc);
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void drm_crtc_set_max_vblank_count(struct drm_crtc *crtc,
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u32 max_vblank_count);
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/*
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* Helpers for struct drm_crtc_funcs
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*/
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typedef bool (*drm_vblank_get_scanout_position_func)(struct drm_crtc *crtc,
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bool in_vblank_irq,
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int *vpos, int *hpos,
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ktime_t *stime,
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ktime_t *etime,
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const struct drm_display_mode *mode);
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bool
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drm_crtc_vblank_helper_get_vblank_timestamp_internal(struct drm_crtc *crtc,
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int *max_error,
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ktime_t *vblank_time,
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bool in_vblank_irq,
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drm_vblank_get_scanout_position_func get_scanout_position);
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bool drm_crtc_vblank_helper_get_vblank_timestamp(struct drm_crtc *crtc,
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int *max_error,
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ktime_t *vblank_time,
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bool in_vblank_irq);
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#endif
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